Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-20 Thread Hans de Goede 

Hi,

On 04/20/2018 04:13 PM, Guenter Roeck wrote:

On 04/20/2018 03:51 AM, Jun Li wrote:



-Original Message-
From: Hans de Goede [mailto:hdego...@redhat.com]
Sent: 2018年4月20日 17:21
To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
heikki.kroge...@linux.intel.com
Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org; dl-linux-imx
<linux-...@nxp.com>
Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

Hi,

On 20-04-18 11:18, Jun Li wrote:



-Original Message-
From: Hans de Goede [mailto:hdego...@redhat.com]
Sent: 2018年4月18日 19:40
To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
heikki.kroge...@linux.intel.com
Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org;
dl-linux-imx <linux-...@nxp.com>
Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw
for rdo

Hi,

On 17-04-18 08:01, Li Jun wrote:

This patch is a further update for rdo based on [1], which removed
max_snk_ma/mv/mw but kept operating_snk_mw.
operating_snk_mw is only used to judge capability mismatch, per PD
spec, we can achieve this via compare the selected source PDO and
matching sink PDO, also after patch [1], we don't limit the PDO
matching between the same type, so the rdo operating and max
current/power calculation should be updated accordingly.


I do not believe that this is correct, lets take a device with a
fusb302 tcpc with the following PDO-s:

PDO_FIXED(5000, 400, PDO_FIXED_FLAGS)
PDO_VAR(5000, 12000, 3000);

And an operating_snk_mw of 2500mW then according to your new code a
charger which supplies 12V 2A will now get the mismatch bit set even
though it is delivering 24W.



Per PD spec, my understanding is to judge capability mismatch, we
should use *max* current/power, not this operating power.


Ok, I'm not familiar with the PD spec, perhaps someone who knows it well can
comment here ?


Hi Guenter,
Could you please comment here?



I am not, and never was, the kind of person who would blindly follow a 
specification.
I use specifications as guideline. For PD, when I implemented the code, I made 
sure
that the implementation worked with as many power adapters and dongles as I 
could get
my hand on.

At this point in time, I would only change the code myself if it is known to be 
broken.
Otherwise I would leave it alone. I would _never_ make a change because my 
interpretation
of the specification is different, unless I can prove that the current code is 
wrong and
causes problems.

Unfortunately, I don't currently have a setup to test the current version of 
the code,
nor the time to do all the testing. I am more and more concerned, though, that 
changes
are made out of principle, not because something has been shown to be broken. 
But that is
just a personal concern, and without re-testing everything I don't really have 
a strong
case for or against those changes.


AFAIK Jun Li's previous series was actually necessary because some boards only
contain some input voltages rather then a range, so that series was triggered
by an actual problem encountered with real hardware, right Jun Li ?

But yes this patch feels like a change purely based on a (re)interpretation
of the SPEC, so lets drop this change and keep the current behavior.

Regards,

Hans






Guenter


Thanks
Jun




In your case(VAR PDO), the max current is 3000mA, can I say the max
power is 3000mA * 5V = 15W? so the max current required at 12V is 15W
/ 12V = 1.25A, so yes, the 12V@2A is enough, do you think this kind of
calculation is reasonable?


That does not sound unreasonable, the real question is when exactly should we
set the capability mismatch bit, once we have that more clear how to
implement this should become clear too.


Fully agree, below is the capability mismatch bit related description from PD 
spec:

"If the Capability Mismatch bit is set to one
The Maximum Operating Current/Power field may contain a value larger than
the maximum current/power offered in the Source_Capabilities Message’s PDO
as referenced by the Object position field. This enables the Sink to indicate 
that
it requires more current/power than is being offered. If the Sink requires a
different voltage this will be indicated by its Sink_Capabilities Message."

"6.4.2.8 Maximum Operating Current
The Maximum Operating Current field in the Request Message shall be set to
the highest current the Sink will ever require. The difference between
the Operating Current and Maximum Operating Current fields
(when the GiveBack Flag is cleared) is used by the Device Policy Manager
in the Source to calculate the size of the Power Reserve to be maintained
(see Section 8.2.5.1). The Operating Current value shall be less than or
equal to the Maximum Operating Current value.
When the Capabilities Mismatch bit is set to zero the requested Maximum 
Operating
Current shall be less than or equal to the current in the offered Source 
Capabilities
since the Source will need to reserve this power fo

Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-20 Thread Guenter Roeck 

On 04/20/2018 03:51 AM, Jun Li wrote:



-Original Message-
From: Hans de Goede [mailto:hdego...@redhat.com]
Sent: 2018年4月20日 17:21
To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
heikki.kroge...@linux.intel.com
Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org; dl-linux-imx
<linux-...@nxp.com>
Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

Hi,

On 20-04-18 11:18, Jun Li wrote:



-Original Message-
From: Hans de Goede [mailto:hdego...@redhat.com]
Sent: 2018年4月18日 19:40
To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
heikki.kroge...@linux.intel.com
Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org;
dl-linux-imx <linux-...@nxp.com>
Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw
for rdo

Hi,

On 17-04-18 08:01, Li Jun wrote:

This patch is a further update for rdo based on [1], which removed
max_snk_ma/mv/mw but kept operating_snk_mw.
operating_snk_mw is only used to judge capability mismatch, per PD
spec, we can achieve this via compare the selected source PDO and
matching sink PDO, also after patch [1], we don't limit the PDO
matching between the same type, so the rdo operating and max
current/power calculation should be updated accordingly.


I do not believe that this is correct, lets take a device with a
fusb302 tcpc with the following PDO-s:

PDO_FIXED(5000, 400, PDO_FIXED_FLAGS)
PDO_VAR(5000, 12000, 3000);

And an operating_snk_mw of 2500mW then according to your new code a
charger which supplies 12V 2A will now get the mismatch bit set even
though it is delivering 24W.



Per PD spec, my understanding is to judge capability mismatch, we
should use *max* current/power, not this operating power.


Ok, I'm not familiar with the PD spec, perhaps someone who knows it well can
comment here ?


Hi Guenter,
Could you please comment here?



I am not, and never was, the kind of person who would blindly follow a 
specification.
I use specifications as guideline. For PD, when I implemented the code, I made 
sure
that the implementation worked with as many power adapters and dongles as I 
could get
my hand on.

At this point in time, I would only change the code myself if it is known to be 
broken.
Otherwise I would leave it alone. I would _never_ make a change because my 
interpretation
of the specification is different, unless I can prove that the current code is 
wrong and
causes problems.

Unfortunately, I don't currently have a setup to test the current version of 
the code,
nor the time to do all the testing. I am more and more concerned, though, that 
changes
are made out of principle, not because something has been shown to be broken. 
But that is
just a personal concern, and without re-testing everything I don't really have 
a strong
case for or against those changes.

Guenter


Thanks
Jun




In your case(VAR PDO), the max current is 3000mA, can I say the max
power is 3000mA * 5V = 15W? so the max current required at 12V is 15W
/ 12V = 1.25A, so yes, the 12V@2A is enough, do you think this kind of
calculation is reasonable?


That does not sound unreasonable, the real question is when exactly should we
set the capability mismatch bit, once we have that more clear how to
implement this should become clear too.


Fully agree, below is the capability mismatch bit related description from PD 
spec:

"If the Capability Mismatch bit is set to one
The Maximum Operating Current/Power field may contain a value larger than
the maximum current/power offered in the Source_Capabilities Message’s PDO
as referenced by the Object position field. This enables the Sink to indicate 
that
it requires more current/power than is being offered. If the Sink requires a
different voltage this will be indicated by its Sink_Capabilities Message."

"6.4.2.8 Maximum Operating Current
The Maximum Operating Current field in the Request Message shall be set to
the highest current the Sink will ever require. The difference between
the Operating Current and Maximum Operating Current fields
(when the GiveBack Flag is cleared) is used by the Device Policy Manager
in the Source to calculate the size of the Power Reserve to be maintained
(see Section 8.2.5.1). The Operating Current value shall be less than or
equal to the Maximum Operating Current value.
When the Capabilities Mismatch bit is set to zero the requested Maximum 
Operating
Current shall be less than or equal to the current in the offered Source 
Capabilities
since the Source will need to reserve this power for future use. ...
  
When the Capabilities Mismatch bit is set to one the requested Maximum

Operating Current may be greater than the current in the offered Source
Capabilities since the Source will need this information to ascertain
the Sink’s actual needs".



Regards,

Hans






I really don't see any way to fix this and I believe we should just
keep the operating_snk_mw field.


I had the same worry of breaking existing user

Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-20 Thread Hans de Goede 

Hi,

On 20-04-18 12:51, Jun Li wrote:



-Original Message-
From: Hans de Goede [mailto:hdego...@redhat.com]
Sent: 2018年4月20日 17:21
To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
heikki.kroge...@linux.intel.com
Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org; dl-linux-imx
<linux-...@nxp.com>
Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

Hi,

On 20-04-18 11:18, Jun Li wrote:



-Original Message-
From: Hans de Goede [mailto:hdego...@redhat.com]
Sent: 2018年4月18日 19:40
To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
heikki.kroge...@linux.intel.com
Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org;
dl-linux-imx <linux-...@nxp.com>
Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw
for rdo

Hi,

On 17-04-18 08:01, Li Jun wrote:

This patch is a further update for rdo based on [1], which removed
max_snk_ma/mv/mw but kept operating_snk_mw.
operating_snk_mw is only used to judge capability mismatch, per PD
spec, we can achieve this via compare the selected source PDO and
matching sink PDO, also after patch [1], we don't limit the PDO
matching between the same type, so the rdo operating and max
current/power calculation should be updated accordingly.


I do not believe that this is correct, lets take a device with a
fusb302 tcpc with the following PDO-s:

PDO_FIXED(5000, 400, PDO_FIXED_FLAGS)
PDO_VAR(5000, 12000, 3000);

And an operating_snk_mw of 2500mW then according to your new code a
charger which supplies 12V 2A will now get the mismatch bit set even
though it is delivering 24W.



Per PD spec, my understanding is to judge capability mismatch, we
should use *max* current/power, not this operating power.


Ok, I'm not familiar with the PD spec, perhaps someone who knows it well can
comment here ?


Hi Guenter,
Could you please comment here?

Thanks
Jun




In your case(VAR PDO), the max current is 3000mA, can I say the max
power is 3000mA * 5V = 15W? so the max current required at 12V is 15W
/ 12V = 1.25A, so yes, the 12V@2A is enough, do you think this kind of
calculation is reasonable?


That does not sound unreasonable, the real question is when exactly should we
set the capability mismatch bit, once we have that more clear how to
implement this should become clear too.


Fully agree, below is the capability mismatch bit related description from PD 
spec:

"If the Capability Mismatch bit is set to one
The Maximum Operating Current/Power field may contain a value larger than
the maximum current/power offered in the Source_Capabilities Message’s PDO
as referenced by the Object position field. This enables the Sink to indicate 
that
it requires more current/power than is being offered. If the Sink requires a
different voltage this will be indicated by its Sink_Capabilities Message."

"6.4.2.8 Maximum Operating Current
The Maximum Operating Current field in the Request Message shall be set to
the highest current the Sink will ever require. The difference between
the Operating Current and Maximum Operating Current fields
(when the GiveBack Flag is cleared) is used by the Device Policy Manager
in the Source to calculate the size of the Power Reserve to be maintained
(see Section 8.2.5.1). The Operating Current value shall be less than or
equal to the Maximum Operating Current value.
When the Capabilities Mismatch bit is set to zero the requested Maximum 
Operating
Current shall be less than or equal to the current in the offered Source 
Capabilities
since the Source will need to reserve this power for future use. ...
  
When the Capabilities Mismatch bit is set to one the requested Maximum

Operating Current may be greater than the current in the offered Source
Capabilities since the Source will need this information to ascertain
the Sink’s actual needs".


Thank you for looking that up, so to what value are we setting the
"Maximum Operating Current" field in the request we are sending?

Regards,

Hans







Regards,

Hans






I really don't see any way to fix this and I believe we should just
keep the operating_snk_mw field.


I had the same worry of breaking existing users, but found there is
something not matching PD spec, so want to get comments, if we really
need another input (beside sink PDO) in practice, we can keep it.

Thanks
Jun


Regards

Hans




[1]https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%
2F




patchwork.kernel.org%2Fpatch%2F10342299%2F=02%7C01%7Cjun.li%4

0nxp

.com%7C796c943804cc4a333a7c08d5a5212e41%7C686ea1d3bc2b4c6fa9

2cd

99c5c30





1635%7C0%7C0%7C636596484284807487=BH74zzVppAi7Fa8jtRt2cwc

d%2F%2F

o6idNC5hk5zyoWIA4%3D=0

Signed-off-by: Li Jun <jun...@nxp.com>
---
drivers/usb/typec/tcpm.c | 52

++--

1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
index
27192083..0be04b3 100644
-

RE: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-20 Thread Jun Li 

> -Original Message-
> From: Hans de Goede [mailto:hdego...@redhat.com]
> Sent: 2018年4月20日 17:21
> To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
> heikki.kroge...@linux.intel.com
> Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org; dl-linux-imx
> <linux-...@nxp.com>
> Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo
> 
> Hi,
> 
> On 20-04-18 11:18, Jun Li wrote:
> >
> >> -Original Message-
> >> From: Hans de Goede [mailto:hdego...@redhat.com]
> >> Sent: 2018年4月18日 19:40
> >> To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
> >> heikki.kroge...@linux.intel.com
> >> Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org;
> >> dl-linux-imx <linux-...@nxp.com>
> >> Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw
> >> for rdo
> >>
> >> Hi,
> >>
> >> On 17-04-18 08:01, Li Jun wrote:
> >>> This patch is a further update for rdo based on [1], which removed
> >>> max_snk_ma/mv/mw but kept operating_snk_mw.
> >>> operating_snk_mw is only used to judge capability mismatch, per PD
> >>> spec, we can achieve this via compare the selected source PDO and
> >>> matching sink PDO, also after patch [1], we don't limit the PDO
> >>> matching between the same type, so the rdo operating and max
> >>> current/power calculation should be updated accordingly.
> >>
> >> I do not believe that this is correct, lets take a device with a
> >> fusb302 tcpc with the following PDO-s:
> >>
> >>PDO_FIXED(5000, 400, PDO_FIXED_FLAGS)
> >>PDO_VAR(5000, 12000, 3000);
> >>
> >> And an operating_snk_mw of 2500mW then according to your new code a
> >> charger which supplies 12V 2A will now get the mismatch bit set even
> >> though it is delivering 24W.
> >>
> >
> > Per PD spec, my understanding is to judge capability mismatch, we
> > should use *max* current/power, not this operating power.
> 
> Ok, I'm not familiar with the PD spec, perhaps someone who knows it well can
> comment here ?

Hi Guenter,
Could you please comment here?

Thanks
Jun

> 
> > In your case(VAR PDO), the max current is 3000mA, can I say the max
> > power is 3000mA * 5V = 15W? so the max current required at 12V is 15W
> > / 12V = 1.25A, so yes, the 12V@2A is enough, do you think this kind of
> > calculation is reasonable?
> 
> That does not sound unreasonable, the real question is when exactly should we
> set the capability mismatch bit, once we have that more clear how to
> implement this should become clear too.

Fully agree, below is the capability mismatch bit related description from PD 
spec:

"If the Capability Mismatch bit is set to one
The Maximum Operating Current/Power field may contain a value larger than
the maximum current/power offered in the Source_Capabilities Message’s PDO
as referenced by the Object position field. This enables the Sink to indicate 
that
it requires more current/power than is being offered. If the Sink requires a
different voltage this will be indicated by its Sink_Capabilities Message."

"6.4.2.8 Maximum Operating Current
The Maximum Operating Current field in the Request Message shall be set to
the highest current the Sink will ever require. The difference between
the Operating Current and Maximum Operating Current fields
(when the GiveBack Flag is cleared) is used by the Device Policy Manager
in the Source to calculate the size of the Power Reserve to be maintained
(see Section 8.2.5.1). The Operating Current value shall be less than or
equal to the Maximum Operating Current value.
When the Capabilities Mismatch bit is set to zero the requested Maximum 
Operating
Current shall be less than or equal to the current in the offered Source 
Capabilities
since the Source will need to reserve this power for future use. ...
 
When the Capabilities Mismatch bit is set to one the requested Maximum
Operating Current may be greater than the current in the offered Source
Capabilities since the Source will need this information to ascertain
the Sink’s actual needs".

> 
> Regards,
> 
> Hans
> 
> 
> 
> >
> >> I really don't see any way to fix this and I believe we should just
> >> keep the operating_snk_mw field.
> >
> > I had the same worry of breaking existing users, but found there is
> > something not matching PD spec, so want to get comments, if we really
> > need another input (beside sink PDO) in practice, we can keep it.
> >
> > Thanks
> > Jun
> >>
> >> Regards
> >>
> >> Hans
> >>
>

Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-20 Thread Hans de Goede 

Hi,

On 20-04-18 11:18, Jun Li wrote:



-Original Message-
From: Hans de Goede [mailto:hdego...@redhat.com]
Sent: 2018年4月18日 19:40
To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
heikki.kroge...@linux.intel.com
Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org; dl-linux-imx
<linux-...@nxp.com>
Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

Hi,

On 17-04-18 08:01, Li Jun wrote:

This patch is a further update for rdo based on [1], which removed
max_snk_ma/mv/mw but kept operating_snk_mw.
operating_snk_mw is only used to judge capability mismatch, per PD
spec, we can achieve this via compare the selected source PDO and
matching sink PDO, also after patch [1], we don't limit the PDO
matching between the same type, so the rdo operating and max
current/power calculation should be updated accordingly.


I do not believe that this is correct, lets take a device with a fusb302 tcpc 
with
the following PDO-s:

PDO_FIXED(5000, 400, PDO_FIXED_FLAGS)
PDO_VAR(5000, 12000, 3000);

And an operating_snk_mw of 2500mW then according to your new code a
charger which supplies 12V 2A will now get the mismatch bit set even though it
is delivering 24W.



Per PD spec, my understanding is to judge capability mismatch, we should
use *max* current/power, not this operating power.


Ok, I'm not familiar with the PD spec, perhaps someone who knows it well
can comment here ?


In your case(VAR PDO), the max current is 3000mA, can I say the max
power is 3000mA * 5V = 15W? so the max current required at 12V
is 15W / 12V = 1.25A, so yes, the 12V@2A is enough, do you think
this kind of calculation is reasonable?


That does not sound unreasonable, the real question is when exactly should
we set the capability mismatch bit, once we have that more clear how to
implement this should become clear too.

Regards,

Hans






I really don't see any way to fix this and I believe we should just keep the
operating_snk_mw field.


I had the same worry of breaking existing users, but found there is something
not matching PD spec, so want to get comments, if we really need another input
(beside sink PDO) in practice, we can keep it.

Thanks
Jun


Regards

Hans




[1]https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2F


patchwork.kernel.org%2Fpatch%2F10342299%2F=02%7C01%7Cjun.li%4
0nxp

.com%7C796c943804cc4a333a7c08d5a5212e41%7C686ea1d3bc2b4c6fa92cd

99c5c30



1635%7C0%7C0%7C636596484284807487=BH74zzVppAi7Fa8jtRt2cwc
d%2F%2F

o6idNC5hk5zyoWIA4%3D=0

Signed-off-by: Li Jun <jun...@nxp.com>
---
   drivers/usb/typec/tcpm.c | 52

++--

   1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c index
27192083..0be04b3 100644
--- a/drivers/usb/typec/tcpm.c
+++ b/drivers/usb/typec/tcpm.c
@@ -1854,28 +1854,42 @@ static int tcpm_pd_build_request(struct

tcpm_port *port, u32 *rdo)

else
mv = pdo_min_voltage(pdo);

-   /* Select maximum available current within the sink pdo's limit */
-   if (type == PDO_TYPE_BATT) {
-   mw = min_power(pdo, matching_snk_pdo);
-   ma = 1000 * mw / mv;
-   } else {
-   ma = min_current(pdo, matching_snk_pdo);
-   mw = ma * mv / 1000;
-   }
-
flags = RDO_USB_COMM | RDO_NO_SUSPEND;

-   /* Set mismatch bit if offered power is less than operating power */
-   max_ma = ma;
-   max_mw = mw;
-   if (mw < port->operating_snk_mw) {
-   flags |= RDO_CAP_MISMATCH;
-   if (type == PDO_TYPE_BATT &&
-   (pdo_max_power(matching_snk_pdo) > pdo_max_power(pdo)))
-   max_mw = pdo_max_power(matching_snk_pdo);
-   else if (pdo_max_current(matching_snk_pdo) >
-pdo_max_current(pdo))
+   switch (type) {
+   case PDO_TYPE_FIXED:
+   case PDO_TYPE_VAR:
+   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
+   max_ma = pdo_max_power(matching_snk_pdo) * 1000 / mv;
+   else
max_ma = pdo_max_current(matching_snk_pdo);
+
+   if (max_ma > pdo_max_current(pdo)) {
+   flags |= RDO_CAP_MISMATCH;
+   ma = pdo_max_current(pdo);
+   } else {
+   ma = max_ma;
+   }
+   break;
+   case PDO_TYPE_BATT:
+   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
+   max_mw = pdo_max_power(matching_snk_pdo);
+   else
+   max_mw = pdo_max_current(matching_snk_pdo) *
+pdo_min_voltage(matching_snk_pdo) /
+1000;
+
+   if (max_mw > pdo_max_power(pdo)) {
+   flags |= RDO_CAP_MISMATCH;
+   mw

RE: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-20 Thread Jun Li 

> -Original Message-
> From: Hans de Goede [mailto:hdego...@redhat.com]
> Sent: 2018年4月18日 19:40
> To: Jun Li <jun...@nxp.com>; li...@roeck-us.net;
> heikki.kroge...@linux.intel.com
> Cc: gre...@linuxfoundation.org; linux-usb@vger.kernel.org; dl-linux-imx
> <linux-...@nxp.com>
> Subject: Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo
> 
> Hi,
> 
> On 17-04-18 08:01, Li Jun wrote:
> > This patch is a further update for rdo based on [1], which removed
> > max_snk_ma/mv/mw but kept operating_snk_mw.
> > operating_snk_mw is only used to judge capability mismatch, per PD
> > spec, we can achieve this via compare the selected source PDO and
> > matching sink PDO, also after patch [1], we don't limit the PDO
> > matching between the same type, so the rdo operating and max
> > current/power calculation should be updated accordingly.
> 
> I do not believe that this is correct, lets take a device with a fusb302 tcpc 
> with
> the following PDO-s:
> 
>   PDO_FIXED(5000, 400, PDO_FIXED_FLAGS)
>   PDO_VAR(5000, 12000, 3000);
> 
> And an operating_snk_mw of 2500mW then according to your new code a
> charger which supplies 12V 2A will now get the mismatch bit set even though it
> is delivering 24W.
> 

Per PD spec, my understanding is to judge capability mismatch, we should
use *max* current/power, not this operating power.

In your case(VAR PDO), the max current is 3000mA, can I say the max
power is 3000mA * 5V = 15W? so the max current required at 12V
is 15W / 12V = 1.25A, so yes, the 12V@2A is enough, do you think
this kind of calculation is reasonable? 

> I really don't see any way to fix this and I believe we should just keep the
> operating_snk_mw field.

I had the same worry of breaking existing users, but found there is something
not matching PD spec, so want to get comments, if we really need another input
(beside sink PDO) in practice, we can keep it.

Thanks
Jun
> 
> Regards
> 
> Hans
> 
> 
> 
> > [1]https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2F
> >
> patchwork.kernel.org%2Fpatch%2F10342299%2F=02%7C01%7Cjun.li%4
> 0nxp
> > .com%7C796c943804cc4a333a7c08d5a5212e41%7C686ea1d3bc2b4c6fa92cd
> 99c5c30
> >
> 1635%7C0%7C0%7C636596484284807487=BH74zzVppAi7Fa8jtRt2cwc
> d%2F%2F
> > o6idNC5hk5zyoWIA4%3D=0
> >
> > Signed-off-by: Li Jun <jun...@nxp.com>
> > ---
> >   drivers/usb/typec/tcpm.c | 52
> ++--
> >   1 file changed, 33 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c index
> > 27192083..0be04b3 100644
> > --- a/drivers/usb/typec/tcpm.c
> > +++ b/drivers/usb/typec/tcpm.c
> > @@ -1854,28 +1854,42 @@ static int tcpm_pd_build_request(struct
> tcpm_port *port, u32 *rdo)
> > else
> > mv = pdo_min_voltage(pdo);
> >
> > -   /* Select maximum available current within the sink pdo's limit */
> > -   if (type == PDO_TYPE_BATT) {
> > -   mw = min_power(pdo, matching_snk_pdo);
> > -   ma = 1000 * mw / mv;
> > -   } else {
> > -   ma = min_current(pdo, matching_snk_pdo);
> > -   mw = ma * mv / 1000;
> > -   }
> > -
> > flags = RDO_USB_COMM | RDO_NO_SUSPEND;
> >
> > -   /* Set mismatch bit if offered power is less than operating power */
> > -   max_ma = ma;
> > -   max_mw = mw;
> > -   if (mw < port->operating_snk_mw) {
> > -   flags |= RDO_CAP_MISMATCH;
> > -   if (type == PDO_TYPE_BATT &&
> > -   (pdo_max_power(matching_snk_pdo) > pdo_max_power(pdo)))
> > -   max_mw = pdo_max_power(matching_snk_pdo);
> > -   else if (pdo_max_current(matching_snk_pdo) >
> > -pdo_max_current(pdo))
> > +   switch (type) {
> > +   case PDO_TYPE_FIXED:
> > +   case PDO_TYPE_VAR:
> > +   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
> > +   max_ma = pdo_max_power(matching_snk_pdo) * 1000 / mv;
> > +   else
> > max_ma = pdo_max_current(matching_snk_pdo);
> > +
> > +   if (max_ma > pdo_max_current(pdo)) {
> > +   flags |= RDO_CAP_MISMATCH;
> > +   ma = pdo_max_current(pdo);
> > +   } else {
> > +   ma = max_ma;
> > +   }
> > +   break;
> > +   case PDO_TYPE_BATT:
> > +   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
> > +   max_mw = pdo_max_power(matchin

Re: [PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-18 Thread Hans de Goede 

Hi,

On 17-04-18 08:01, Li Jun wrote:

This patch is a further update for rdo based on [1], which
removed max_snk_ma/mv/mw but kept operating_snk_mw.
operating_snk_mw is only used to judge capability mismatch,
per PD spec, we can achieve this via compare the selected
source PDO and matching sink PDO, also after patch [1], we
don't limit the PDO matching between the same type, so the
rdo operating and max current/power calculation should be
updated accordingly.


I do not believe that this is correct, lets take a device
with a fusb302 tcpc with the following PDO-s:

PDO_FIXED(5000, 400, PDO_FIXED_FLAGS)
PDO_VAR(5000, 12000, 3000);

And an operating_snk_mw of 2500mW then according to your
new code a charger which supplies 12V 2A will now get
the mismatch bit set even though it is delivering 24W.

I really don't see any way to fix this and I believe we
should just keep the operating_snk_mw field.

Regards

Hans




[1]https://patchwork.kernel.org/patch/10342299/

Signed-off-by: Li Jun 
---
  drivers/usb/typec/tcpm.c | 52 ++--
  1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
index 27192083..0be04b3 100644
--- a/drivers/usb/typec/tcpm.c
+++ b/drivers/usb/typec/tcpm.c
@@ -1854,28 +1854,42 @@ static int tcpm_pd_build_request(struct tcpm_port 
*port, u32 *rdo)
else
mv = pdo_min_voltage(pdo);
  
-	/* Select maximum available current within the sink pdo's limit */

-   if (type == PDO_TYPE_BATT) {
-   mw = min_power(pdo, matching_snk_pdo);
-   ma = 1000 * mw / mv;
-   } else {
-   ma = min_current(pdo, matching_snk_pdo);
-   mw = ma * mv / 1000;
-   }
-
flags = RDO_USB_COMM | RDO_NO_SUSPEND;
  
-	/* Set mismatch bit if offered power is less than operating power */

-   max_ma = ma;
-   max_mw = mw;
-   if (mw < port->operating_snk_mw) {
-   flags |= RDO_CAP_MISMATCH;
-   if (type == PDO_TYPE_BATT &&
-   (pdo_max_power(matching_snk_pdo) > pdo_max_power(pdo)))
-   max_mw = pdo_max_power(matching_snk_pdo);
-   else if (pdo_max_current(matching_snk_pdo) >
-pdo_max_current(pdo))
+   switch (type) {
+   case PDO_TYPE_FIXED:
+   case PDO_TYPE_VAR:
+   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
+   max_ma = pdo_max_power(matching_snk_pdo) * 1000 / mv;
+   else
max_ma = pdo_max_current(matching_snk_pdo);
+
+   if (max_ma > pdo_max_current(pdo)) {
+   flags |= RDO_CAP_MISMATCH;
+   ma = pdo_max_current(pdo);
+   } else {
+   ma = max_ma;
+   }
+   break;
+   case PDO_TYPE_BATT:
+   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
+   max_mw = pdo_max_power(matching_snk_pdo);
+   else
+   max_mw = pdo_max_current(matching_snk_pdo) *
+pdo_min_voltage(matching_snk_pdo) /
+1000;
+
+   if (max_mw > pdo_max_power(pdo)) {
+   flags |= RDO_CAP_MISMATCH;
+   mw = pdo_max_power(pdo);
+   } else {
+   mw = max_mw;
+   }
+
+   ma = mw * 1000 / mv;
+   break;
+   default:
+   break;
}
  
  	tcpm_log(port, "cc=%d cc1=%d cc2=%d vbus=%d vconn=%s polarity=%d",



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[PATCH RFC] usb: typec: tcpm: remove operating_snk_mw for rdo

2018-04-17 Thread Li Jun 
This patch is a further update for rdo based on [1], which
removed max_snk_ma/mv/mw but kept operating_snk_mw.
operating_snk_mw is only used to judge capability mismatch,
per PD spec, we can achieve this via compare the selected
source PDO and matching sink PDO, also after patch [1], we
don't limit the PDO matching between the same type, so the
rdo operating and max current/power calculation should be
updated accordingly.

[1]https://patchwork.kernel.org/patch/10342299/

Signed-off-by: Li Jun 
---
 drivers/usb/typec/tcpm.c | 52 ++--
 1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
index 27192083..0be04b3 100644
--- a/drivers/usb/typec/tcpm.c
+++ b/drivers/usb/typec/tcpm.c
@@ -1854,28 +1854,42 @@ static int tcpm_pd_build_request(struct tcpm_port 
*port, u32 *rdo)
else
mv = pdo_min_voltage(pdo);
 
-   /* Select maximum available current within the sink pdo's limit */
-   if (type == PDO_TYPE_BATT) {
-   mw = min_power(pdo, matching_snk_pdo);
-   ma = 1000 * mw / mv;
-   } else {
-   ma = min_current(pdo, matching_snk_pdo);
-   mw = ma * mv / 1000;
-   }
-
flags = RDO_USB_COMM | RDO_NO_SUSPEND;
 
-   /* Set mismatch bit if offered power is less than operating power */
-   max_ma = ma;
-   max_mw = mw;
-   if (mw < port->operating_snk_mw) {
-   flags |= RDO_CAP_MISMATCH;
-   if (type == PDO_TYPE_BATT &&
-   (pdo_max_power(matching_snk_pdo) > pdo_max_power(pdo)))
-   max_mw = pdo_max_power(matching_snk_pdo);
-   else if (pdo_max_current(matching_snk_pdo) >
-pdo_max_current(pdo))
+   switch (type) {
+   case PDO_TYPE_FIXED:
+   case PDO_TYPE_VAR:
+   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
+   max_ma = pdo_max_power(matching_snk_pdo) * 1000 / mv;
+   else
max_ma = pdo_max_current(matching_snk_pdo);
+
+   if (max_ma > pdo_max_current(pdo)) {
+   flags |= RDO_CAP_MISMATCH;
+   ma = pdo_max_current(pdo);
+   } else {
+   ma = max_ma;
+   }
+   break;
+   case PDO_TYPE_BATT:
+   if (pdo_type(matching_snk_pdo) == PDO_TYPE_BATT)
+   max_mw = pdo_max_power(matching_snk_pdo);
+   else
+   max_mw = pdo_max_current(matching_snk_pdo) *
+pdo_min_voltage(matching_snk_pdo) /
+1000;
+
+   if (max_mw > pdo_max_power(pdo)) {
+   flags |= RDO_CAP_MISMATCH;
+   mw = pdo_max_power(pdo);
+   } else {
+   mw = max_mw;
+   }
+
+   ma = mw * 1000 / mv;
+   break;
+   default:
+   break;
}
 
tcpm_log(port, "cc=%d cc1=%d cc2=%d vbus=%d vconn=%s polarity=%d",
-- 
2.7.4

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