Re: [U-Boot] [PATCH v2 1/3] mx6: ddr: Adjust MDREF register settings for MX6UL

2016-08-29 Thread Eric Nelson 
Hi Fabio,

On 08/29/2016 12:53 PM, Fabio Estevam wrote:
> Hi Eric,
> 
> On Mon, Aug 29, 2016 at 3:48 PM, Eric Nelson  wrote:
> 
>> I think this commit message needs work.
>>
>> "we have" seems to mean that the NXP U-Boot fork has this
>> setting, but this isn't an explanation of why.
> 
> Would you prefer something like this in ddr.c?
> http://pastebin.com/GYBTSFkM
> 
> and then on the board file:
> 
> http://pastebin.com/cEqvUJwg
> 

I'm actually not sure because I haven't quite figured out
where the 32k and 64k clock roots are being passed into
the MMDC.

If these are configured in a way that allow the kernel
implementations to disable one of them, then this should
be a board-specific setting to allow different choices.

Or is the inability to use the 64k clock driven by the
i.MX6UL somehow? If that's the case, then your original
patch is more correct.

I'm also not sure why the NXP U-Boot is decreasing the
refresh rate on the 6UL EVK.

Regards,


Eric
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Re: [U-Boot] [PATCH v2 1/3] mx6: ddr: Adjust MDREF register settings for MX6UL

2016-08-29 Thread Fabio Estevam 
Hi Eric,

On Mon, Aug 29, 2016 at 3:48 PM, Eric Nelson  wrote:

> I think this commit message needs work.
>
> "we have" seems to mean that the NXP U-Boot fork has this
> setting, but this isn't an explanation of why.

Would you prefer something like this in ddr.c?
http://pastebin.com/GYBTSFkM

and then on the board file:

http://pastebin.com/cEqvUJwg
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Re: [U-Boot] [PATCH v2 1/3] mx6: ddr: Adjust MDREF register settings for MX6UL

2016-08-29 Thread Eric Nelson 
Hi Fabio,

On 08/29/2016 11:48 AM, Eric Nelson wrote:
> Hi Fabio,
> 
> On 08/29/2016 10:56 AM, Fabio Estevam wrote:
>> From: Fabio Estevam 
>>
>> When running a NXP 4.1 kernel with U-Boot mainline we observe a
>> hang when going into the lowest operational point of cpufreq.
>>
>> After comparing the SPL DDR initialization against the DCD table
>> from NXP U-Boot, the key difference that causes the hang is the
>> MDREF register setting.
>>
>> In all the DDR3 MX6UL boards we have the following configuration
>> for MDREF:
>>
> 
> I think this commit message needs work.
> 
> "we have" seems to mean that the NXP U-Boot fork has this
> setting, but this isn't an explanation of why.
> 

After reviewing the manual, I think I understand why this
is needed and something like this is probably better:

The i.MX6UL kernel uses a 32kHz clock for to drive refresh in
low power mode. Configure the MMDC to use it as the input for
refresh in MMDC_MDREF.

>> DATA 4 0x021B0020 0x0800
>>
>> ,which means:
>>
>> REF_SEL = 0 -->Periodic refresh cycle: 64kHz 
>> REFR = 1 ---> Refresh Rate - 2 refreshes
>>
>> So adjust the MDREF initialization for MX6UL to fix the kernel
>> hang issue.
>>
>> Reported-by: Eric Nelson 
>> Signed-off-by: Fabio Estevam 
>> ---
>> Changes since v1:
>> - Newly introduced in this version
>>
>>  arch/arm/cpu/armv7/mx6/ddr.c | 12 +---
>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/cpu/armv7/mx6/ddr.c b/arch/arm/cpu/armv7/mx6/ddr.c
>> index f151eec..56d3e65 100644
>> --- a/arch/arm/cpu/armv7/mx6/ddr.c
>> +++ b/arch/arm/cpu/armv7/mx6/ddr.c
>> @@ -1183,7 +1183,7 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo 
>> *sysinfo,
>>  volatile struct mmdc_p_regs *mmdc0;
>>  volatile struct mmdc_p_regs *mmdc1;
>>  u32 val;
>> -u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd;
>> +u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd, refr, refsel;
>>  u8 todtlon, taxpd, tanpd, tcwl, txp, tfaw, tcl;
>>  u8 todt_idle_off = 0x4; /* from DDR3 Script Aid spreadsheet */
>>  u16 trcd, trc, tras, twr, tmrd, trtp, trp, twtr, trfc, txs, txpr;
>> @@ -1472,9 +1472,15 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo 
>> *sysinfo,
>>  MMDC1(mpzqhwctrl, val);
>>
>>  /* Step 12: Configure and activate periodic refresh */
>> -mmdc0->mdref = (1 << 14) | /* REF_SEL: Periodic refresh cycle: 32kHz */
>> -   (7 << 11);  /* REFR: Refresh Rate - 8 refreshes */
> 
> I'm not understanding why this is CPU specific. Is the issue
> 
>> +if (!is_mx6ul()) {
> 
> Table 44-15 of the 6DQ reference manual says that this will generate
> tREFI at 3.9uS (256kHz).
> 

Never mind. Your comment is about the input clock, not the refresh
cycle.

I do wonder if both of these settings don't over-refresh the DDR3
though.

>> +refsel = 1; /* REF_SEL: Periodic refresh cycle: 32kHz */
>> +refr = 7;   /* REFR: Refresh Rate - 8 refreshes */
>> +} else {
> 
> Table 33-15 of the 6UL manual says 7.8us (128 kHz).
> 
>> +refsel = 0; /* REF_SEL: Periodic refresh cycle: 64kHz */
>> +refr = 1;   /* REFR: Refresh Rate - 2 refreshes */
>> +}
>>  
>> +mmdc0->mdref = (refsel << 14) | (refr << 11);
>>  /* Step 13: Deassert config request - init complete */
>>  mmdc0->mdscr = 0x;
>>  
>>
> 
> I did test this patch though, and I can confirm that the problem
> I experienced (hang with low bus frequency) goes away with just
> this change, so
> 
> Tested-by: Eric Nelson 
> 

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Re: [U-Boot] [PATCH v2 1/3] mx6: ddr: Adjust MDREF register settings for MX6UL

2016-08-29 Thread Eric Nelson 
Hi Fabio,

On 08/29/2016 10:56 AM, Fabio Estevam wrote:
> From: Fabio Estevam 
> 
> When running a NXP 4.1 kernel with U-Boot mainline we observe a
> hang when going into the lowest operational point of cpufreq.
> 
> After comparing the SPL DDR initialization against the DCD table
> from NXP U-Boot, the key difference that causes the hang is the
> MDREF register setting.
> 
> In all the DDR3 MX6UL boards we have the following configuration
> for MDREF:
> 

I think this commit message needs work.

"we have" seems to mean that the NXP U-Boot fork has this
setting, but this isn't an explanation of why.

> DATA 4 0x021B0020 0x0800
> 
> ,which means:
> 
> REF_SEL = 0 -->Periodic refresh cycle: 64kHz 
> REFR = 1 ---> Refresh Rate - 2 refreshes
> 
> So adjust the MDREF initialization for MX6UL to fix the kernel
> hang issue.
> 
> Reported-by: Eric Nelson 
> Signed-off-by: Fabio Estevam 
> ---
> Changes since v1:
> - Newly introduced in this version
> 
>  arch/arm/cpu/armv7/mx6/ddr.c | 12 +---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/cpu/armv7/mx6/ddr.c b/arch/arm/cpu/armv7/mx6/ddr.c
> index f151eec..56d3e65 100644
> --- a/arch/arm/cpu/armv7/mx6/ddr.c
> +++ b/arch/arm/cpu/armv7/mx6/ddr.c
> @@ -1183,7 +1183,7 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo *sysinfo,
>   volatile struct mmdc_p_regs *mmdc0;
>   volatile struct mmdc_p_regs *mmdc1;
>   u32 val;
> - u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd;
> + u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd, refr, refsel;
>   u8 todtlon, taxpd, tanpd, tcwl, txp, tfaw, tcl;
>   u8 todt_idle_off = 0x4; /* from DDR3 Script Aid spreadsheet */
>   u16 trcd, trc, tras, twr, tmrd, trtp, trp, twtr, trfc, txs, txpr;
> @@ -1472,9 +1472,15 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo 
> *sysinfo,
>   MMDC1(mpzqhwctrl, val);
>
>   /* Step 12: Configure and activate periodic refresh */
> - mmdc0->mdref = (1 << 14) | /* REF_SEL: Periodic refresh cycle: 32kHz */
> -(7 << 11);  /* REFR: Refresh Rate - 8 refreshes */

I'm not understanding why this is CPU specific. Is the issue

> + if (!is_mx6ul()) {

Table 44-15 of the 6DQ reference manual says that this will generate
tREFI at 3.9uS (256kHz).

> + refsel = 1; /* REF_SEL: Periodic refresh cycle: 32kHz */
> + refr = 7;   /* REFR: Refresh Rate - 8 refreshes */
> + } else {

Table 33-15 of the 6UL manual says 7.8us (128 kHz).

> + refsel = 0; /* REF_SEL: Periodic refresh cycle: 64kHz */
> + refr = 1;   /* REFR: Refresh Rate - 2 refreshes */
> + }
>  
> + mmdc0->mdref = (refsel << 14) | (refr << 11);
>   /* Step 13: Deassert config request - init complete */
>   mmdc0->mdscr = 0x;
>  
> 

I did test this patch though, and I can confirm that the problem
I experienced (hang with low bus frequency) goes away with just
this change, so

Tested-by: Eric Nelson 
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[U-Boot] [PATCH v2 1/3] mx6: ddr: Adjust MDREF register settings for MX6UL

2016-08-29 Thread Fabio Estevam 
From: Fabio Estevam 

When running a NXP 4.1 kernel with U-Boot mainline we observe a
hang when going into the lowest operational point of cpufreq.

After comparing the SPL DDR initialization against the DCD table
from NXP U-Boot, the key difference that causes the hang is the
MDREF register setting.

In all the DDR3 MX6UL boards we have the following configuration
for MDREF:

DATA 4 0x021B0020 0x0800

,which means:

REF_SEL = 0 -->Periodic refresh cycle: 64kHz 
REFR = 1 ---> Refresh Rate - 2 refreshes

So adjust the MDREF initialization for MX6UL to fix the kernel
hang issue.

Reported-by: Eric Nelson 
Signed-off-by: Fabio Estevam 
---
Changes since v1:
- Newly introduced in this version

 arch/arm/cpu/armv7/mx6/ddr.c | 12 +---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/arm/cpu/armv7/mx6/ddr.c b/arch/arm/cpu/armv7/mx6/ddr.c
index f151eec..56d3e65 100644
--- a/arch/arm/cpu/armv7/mx6/ddr.c
+++ b/arch/arm/cpu/armv7/mx6/ddr.c
@@ -1183,7 +1183,7 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo *sysinfo,
volatile struct mmdc_p_regs *mmdc0;
volatile struct mmdc_p_regs *mmdc1;
u32 val;
-   u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd;
+   u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd, refr, refsel;
u8 todtlon, taxpd, tanpd, tcwl, txp, tfaw, tcl;
u8 todt_idle_off = 0x4; /* from DDR3 Script Aid spreadsheet */
u16 trcd, trc, tras, twr, tmrd, trtp, trp, twtr, trfc, txs, txpr;
@@ -1472,9 +1472,15 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo *sysinfo,
MMDC1(mpzqhwctrl, val);
 
/* Step 12: Configure and activate periodic refresh */
-   mmdc0->mdref = (1 << 14) | /* REF_SEL: Periodic refresh cycle: 32kHz */
-  (7 << 11);  /* REFR: Refresh Rate - 8 refreshes */
+   if (!is_mx6ul()) {
+   refsel = 1; /* REF_SEL: Periodic refresh cycle: 32kHz */
+   refr = 7;   /* REFR: Refresh Rate - 8 refreshes */
+   } else {
+   refsel = 0; /* REF_SEL: Periodic refresh cycle: 64kHz */
+   refr = 1;   /* REFR: Refresh Rate - 2 refreshes */
+   }
 
+   mmdc0->mdref = (refsel << 14) | (refr << 11);
/* Step 13: Deassert config request - init complete */
mmdc0->mdscr = 0x;
 
-- 
1.9.1

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[U-Boot] [PATCH v2 1/3] mx6: ddr: Adjust MDREF register settings for MX6UL

2016-08-29 Thread Fabio Estevam 
From: Fabio Estevam 

When running a NXP 4.1 kernel with U-Boot mainline we observe a
hang when going into the lowest operational point of cpufreq.

After comparing the SPL DDR initialization against the DCD table
from NXP U-Boot, the key difference that causes the hang is the
MDREF register setting.

In all the DDR3 MX6UL boards we have the following configuration
for MDREF:

DATA 4 0x021B0020 0x0800

,which means:

REF_SEL = 0 -->Periodic refresh cycle: 64kHz 
REFR = 1 ---> Refresh Rate - 2 refreshes

So adjust the MDREF initialization for MX6UL to fix the kernel
hang issue.

Reported-by: Eric Nelson 
Signed-off-by: Fabio Estevam 
---
Changes since v1:
- Newly introduced in this version

 arch/arm/cpu/armv7/mx6/ddr.c | 12 +---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/arm/cpu/armv7/mx6/ddr.c b/arch/arm/cpu/armv7/mx6/ddr.c
index f151eec..56d3e65 100644
--- a/arch/arm/cpu/armv7/mx6/ddr.c
+++ b/arch/arm/cpu/armv7/mx6/ddr.c
@@ -1183,7 +1183,7 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo *sysinfo,
volatile struct mmdc_p_regs *mmdc0;
volatile struct mmdc_p_regs *mmdc1;
u32 val;
-   u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd;
+   u8 tcke, tcksrx, tcksre, txpdll, taofpd, taonpd, trrd, refr, refsel;
u8 todtlon, taxpd, tanpd, tcwl, txp, tfaw, tcl;
u8 todt_idle_off = 0x4; /* from DDR3 Script Aid spreadsheet */
u16 trcd, trc, tras, twr, tmrd, trtp, trp, twtr, trfc, txs, txpr;
@@ -1472,9 +1472,15 @@ void mx6_ddr3_cfg(const struct mx6_ddr_sysinfo *sysinfo,
MMDC1(mpzqhwctrl, val);
 
/* Step 12: Configure and activate periodic refresh */
-   mmdc0->mdref = (1 << 14) | /* REF_SEL: Periodic refresh cycle: 32kHz */
-  (7 << 11);  /* REFR: Refresh Rate - 8 refreshes */
+   if (!is_mx6ul()) {
+   refsel = 1; /* REF_SEL: Periodic refresh cycle: 32kHz */
+   refr = 7;   /* REFR: Refresh Rate - 8 refreshes */
+   } else {
+   refsel = 0; /* REF_SEL: Periodic refresh cycle: 64kHz */
+   refr = 1;   /* REFR: Refresh Rate - 2 refreshes */
+   }
 
+   mmdc0->mdref = (refsel << 14) | (refr << 11);
/* Step 13: Deassert config request - init complete */
mmdc0->mdscr = 0x;
 
-- 
1.9.1

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