Re: [PATCH v3] usb: gadget: f_midi: Add checking if it need align buffer's size to an ep's maxpacketsize
Hi Felipe,
On 26 July 2016 at 19:06, Felipe Ferreri Tonello wrote:
> Hi Baolin,
>
> Sorry for not replying for previous emails because for some reason these
> emails were archived. :(
>
> On 12/07/16 10:01, Baolin Wang wrote:
>> Some gadget device (such as dwc3 gadget) requires quirk_ep_out_aligned_size
>> attribute, which means it need to align the request buffer's size to an ep's
>> maxpacketsize.
>>
>> Thus we add usb_ep_align_maybe() function to check if it is need to align
>> the request buffer's size to an ep's maxpacketsize.
>>
>> Signed-off-by: Baolin Wang
>> Acked-by: Michal Nazarewicz
>> ---
>> Changelog:
>> v2:
>> - Simplify the method to get buffer length.
>> v1:
>> - Remove the in_ep modification.
>> - Remove max_t() function.
>>
>> drivers/usb/gadget/function/f_midi.c | 11 +++
>> 1 file changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/function/f_midi.c
>> b/drivers/usb/gadget/function/f_midi.c
>> index 58fc199..3486941 100644
>> --- a/drivers/usb/gadget/function/f_midi.c
>> +++ b/drivers/usb/gadget/function/f_midi.c
>> @@ -359,10 +359,13 @@ static int f_midi_set_alt(struct usb_function *f,
>> unsigned intf, unsigned alt)
>>
>> /* allocate a bunch of read buffers and queue them all at once. */
>> for (i = 0; i < midi->qlen && err == 0; i++) {
>> - struct usb_request *req =
>> - midi_alloc_ep_req(midi->out_ep,
>> - max_t(unsigned, midi->buflen,
>> - bulk_out_desc.wMaxPacketSize));
>> + struct usb_request *req;
>> + unsigned length;
>> +
>> + length = usb_ep_align_maybe(midi->gadget, midi->out_ep,
>> + midi->buflen);
>> +
>> + req = midi_alloc_ep_req(midi->out_ep, length);
>> if (req == NULL)
>> return -ENOMEM;
>>
>>
>
> Yes, as mentioned before, my intent was to align the size otherwise an
> actual nasty bug happens.
>
> I have two problems with this approach:
> * usb_ep_align_maybe() has a bug that it doesn't convert wMaxPacketSize
> endianness to the CPU. See my patch on that[1] subject. Also this
Yes, you are right, I missed that.
> function uses round_up which expects x and y to be a power of 2, is that
> a feasible assumption?
I suppose it only expects y is a power of 2.
> * If the gadget driver doesn't support quirk_ep_out_aligned_size,
> usb_ep_align_maybe() can potentially return a len < wMaxPacketSize.
> Basically causing a regression.
Okay.
>
> I believe we should protect this bad behavior on alloc_ep_req() in
> drivers/usb/gadget/u_f.c by forcing align the size if the endpoint in
> subject is OUT.
>
> [1] [PATCH 1/4] usb: gadget: f_midi: fixed endianness when using
> wMaxPacketSize: https://lkml.org/lkml/2016/7/25/1028
--
Baolin.wang
Best Regards
Re: [PATCH v3] usb: gadget: f_midi: Add checking if it need align buffer's size to an ep's maxpacketsize
Hi Baolin,
Sorry for not replying for previous emails because for some reason these
emails were archived. :(
On 12/07/16 10:01, Baolin Wang wrote:
> Some gadget device (such as dwc3 gadget) requires quirk_ep_out_aligned_size
> attribute, which means it need to align the request buffer's size to an ep's
> maxpacketsize.
>
> Thus we add usb_ep_align_maybe() function to check if it is need to align
> the request buffer's size to an ep's maxpacketsize.
>
> Signed-off-by: Baolin Wang
> Acked-by: Michal Nazarewicz
> ---
> Changelog:
> v2:
> - Simplify the method to get buffer length.
> v1:
> - Remove the in_ep modification.
> - Remove max_t() function.
>
> drivers/usb/gadget/function/f_midi.c | 11 +++
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/f_midi.c
> b/drivers/usb/gadget/function/f_midi.c
> index 58fc199..3486941 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -359,10 +359,13 @@ static int f_midi_set_alt(struct usb_function *f,
> unsigned intf, unsigned alt)
>
> /* allocate a bunch of read buffers and queue them all at once. */
> for (i = 0; i < midi->qlen && err == 0; i++) {
> - struct usb_request *req =
> - midi_alloc_ep_req(midi->out_ep,
> - max_t(unsigned, midi->buflen,
> - bulk_out_desc.wMaxPacketSize));
> + struct usb_request *req;
> + unsigned length;
> +
> + length = usb_ep_align_maybe(midi->gadget, midi->out_ep,
> + midi->buflen);
> +
> + req = midi_alloc_ep_req(midi->out_ep, length);
> if (req == NULL)
> return -ENOMEM;
>
>
Yes, as mentioned before, my intent was to align the size otherwise an
actual nasty bug happens.
I have two problems with this approach:
* usb_ep_align_maybe() has a bug that it doesn't convert wMaxPacketSize
endianness to the CPU. See my patch on that[1] subject. Also this
function uses round_up which expects x and y to be a power of 2, is that
a feasible assumption?
* If the gadget driver doesn't support quirk_ep_out_aligned_size,
usb_ep_align_maybe() can potentially return a len < wMaxPacketSize.
Basically causing a regression.
I believe we should protect this bad behavior on alloc_ep_req() in
drivers/usb/gadget/u_f.c by forcing align the size if the endpoint in
subject is OUT.
[1] [PATCH 1/4] usb: gadget: f_midi: fixed endianness when using
wMaxPacketSize: https://lkml.org/lkml/2016/7/25/1028
--
Felipe
0x92698E6A.asc
Description: application/pgp-keys
[PATCH v3] usb: gadget: f_midi: Add checking if it need align buffer's size to an ep's maxpacketsize
Some gadget device (such as dwc3 gadget) requires quirk_ep_out_aligned_size
attribute, which means it need to align the request buffer's size to an ep's
maxpacketsize.
Thus we add usb_ep_align_maybe() function to check if it is need to align
the request buffer's size to an ep's maxpacketsize.
Signed-off-by: Baolin Wang
Acked-by: Michal Nazarewicz
---
Changelog:
v2:
- Simplify the method to get buffer length.
v1:
- Remove the in_ep modification.
- Remove max_t() function.
drivers/usb/gadget/function/f_midi.c | 11 +++
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/gadget/function/f_midi.c
b/drivers/usb/gadget/function/f_midi.c
index 58fc199..3486941 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -359,10 +359,13 @@ static int f_midi_set_alt(struct usb_function *f,
unsigned intf, unsigned alt)
/* allocate a bunch of read buffers and queue them all at once. */
for (i = 0; i < midi->qlen && err == 0; i++) {
- struct usb_request *req =
- midi_alloc_ep_req(midi->out_ep,
- max_t(unsigned, midi->buflen,
- bulk_out_desc.wMaxPacketSize));
+ struct usb_request *req;
+ unsigned length;
+
+ length = usb_ep_align_maybe(midi->gadget, midi->out_ep,
+ midi->buflen);
+
+ req = midi_alloc_ep_req(midi->out_ep, length);
if (req == NULL)
return -ENOMEM;
--
1.7.9.5
