[PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Faraz Ata]

From: Selvarasu Ganesan <selvarasu.g@samsung.com>

The current implementation sets the wMaxPacketSize of bulk in/out
endpoints to 1024 bytes at the end of the f_midi_bind function. However,
in cases where there is a failure in the first midi bind attempt,
consider rebinding. This scenario may encounter an f_midi_bind issue due
to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024
bytes, which exceeds the ep->maxpacket_limit where configured TX/RX
FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS
speed only.
This commit addresses this issue by resetting the wMaxPacketSize before
endpoint claim

Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation")
Cc: stable@vger.kernel.org
Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
---
 drivers/usb/gadget/function/f_midi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 837fcdfa3840..5caa0e4eb07e 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -907,6 +907,15 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
 
 	status = -ENODEV;
 
+	/*
+	 * Reset wMaxPacketSize with maximum packet size of FS bulk transfer before
+	 * endpoint claim. This ensures that the wMaxPacketSize does not exceed the
+	 * limit during bind retries where configured TX/RX FIFO's maxpacket size
+	 * of 512 bytes for IN/OUT endpoints in support HS speed only.
+	 */
+	bulk_in_desc.wMaxPacketSize = cpu_to_le16(64);
+	bulk_out_desc.wMaxPacketSize = cpu_to_le16(64);
+
 	/* allocate instance-specific endpoints */
 	midi->in_ep = usb_ep_autoconfig(cdev->gadget, &bulk_in_desc);
 	if (!midi->in_ep)
-- 
2.17.1

[PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

The current implementation sets the wMaxPacketSize of bulk in/out
endpoints to 1024 bytes at the end of the f_midi_bind function. However,
in cases where there is a failure in the first midi bind attempt,
consider rebinding. This scenario may encounter an f_midi_bind issue due
to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024
bytes, which exceeds the ep->maxpacket_limit where configured TX/RX
FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS
speed only.
This commit addresses this issue by resetting the wMaxPacketSize before
endpoint claim.

Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation")
Cc: stable@vger.kernel.org
Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
---
 drivers/usb/gadget/function/f_midi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 837fcdfa3840..5caa0e4eb07e 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -907,6 +907,15 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
 
 	status = -ENODEV;
 
+	/*
+	 * Reset wMaxPacketSize with maximum packet size of FS bulk transfer before
+	 * endpoint claim. This ensures that the wMaxPacketSize does not exceed the
+	 * limit during bind retries where configured TX/RX FIFO's maxpacket size
+	 * of 512 bytes for IN/OUT endpoints in support HS speed only.
+	 */
+	bulk_in_desc.wMaxPacketSize = cpu_to_le16(64);
+	bulk_out_desc.wMaxPacketSize = cpu_to_le16(64);
+
 	/* allocate instance-specific endpoints */
 	midi->in_ep = usb_ep_autoconfig(cdev->gadget, &bulk_in_desc);
 	if (!midi->in_ep)
-- 
2.17.1

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

Hello Maintainers,

Please ignore this commit as this duplicate copy of 
https://lore.kernel.org/linux-usb/20241208152322.1653-1-selvarasu.g@samsung.com/ 


Thanks,

Selva


On 12/8/2024 8:43 PM, Faraz Ata wrote:
> From: Selvarasu Ganesan <selvarasu.g@samsung.com>
>
> The current implementation sets the wMaxPacketSize of bulk in/out
> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
> in cases where there is a failure in the first midi bind attempt,
> consider rebinding. This scenario may encounter an f_midi_bind issue due
> to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024
> bytes, which exceeds the ep->maxpacket_limit where configured TX/RX
> FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS
> speed only.
> This commit addresses this issue by resetting the wMaxPacketSize before
> endpoint claim
>
> Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
> ---
>   drivers/usb/gadget/function/f_midi.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> index 837fcdfa3840..5caa0e4eb07e 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -907,6 +907,15 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
>   
>   	status = -ENODEV;
>   
> +	/*
> +	 * Reset wMaxPacketSize with maximum packet size of FS bulk transfer before
> +	 * endpoint claim. This ensures that the wMaxPacketSize does not exceed the
> +	 * limit during bind retries where configured TX/RX FIFO's maxpacket size
> +	 * of 512 bytes for IN/OUT endpoints in support HS speed only.
> +	 */
> +	bulk_in_desc.wMaxPacketSize = cpu_to_le16(64);
> +	bulk_out_desc.wMaxPacketSize = cpu_to_le16(64);
> +
>   	/* allocate instance-specific endpoints */
>   	midi->in_ep = usb_ep_autoconfig(cdev->gadget, &bulk_in_desc);
>   	if (!midi->in_ep)

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Greg KH]

On Sun, Dec 08, 2024 at 08:58:32PM +0530, Selvarasu Ganesan wrote:
> Hello Maintainers,
> 
> Please ignore this commit as this duplicate copy of 
> https://lore.kernel.org/linux-usb/20241208152322.1653-1-selvarasu.g@samsung.com/ 

So which is correct?

confused,

greg k-h

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/8/2024 9:18 PM, Greg KH wrote:
> On Sun, Dec 08, 2024 at 08:58:32PM +0530, Selvarasu Ganesan wrote:
>> Hello Maintainers,
>>
>> Please ignore this commit as this duplicate copy of
>> https://lore.kernel.org/linux-usb/20241208152322.1653-1-selvarasu.g@samsung.com/
> So which is correct?
>
> confused,
Sorry for the confusion. The below is the correct one.

https://lore.kernel.org/linux-usb/20241208152322.1653-1-selvarasu.g@samsung.com/


Thanks,
Selva
>
> greg k-h
>
>

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

Hello Maintainers.

Gentle remainder for review.

Thanks,
Selva


On 12/8/2024 8:53 PM, Selvarasu Ganesan wrote:
> The current implementation sets the wMaxPacketSize of bulk in/out
> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
> in cases where there is a failure in the first midi bind attempt,
> consider rebinding. This scenario may encounter an f_midi_bind issue due
> to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024
> bytes, which exceeds the ep->maxpacket_limit where configured TX/RX
> FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS
> speed only.
> This commit addresses this issue by resetting the wMaxPacketSize before
> endpoint claim.
>
> Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
> ---
>   drivers/usb/gadget/function/f_midi.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> index 837fcdfa3840..5caa0e4eb07e 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -907,6 +907,15 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
>   
>   	status = -ENODEV;
>   
> +	/*
> +	 * Reset wMaxPacketSize with maximum packet size of FS bulk transfer before
> +	 * endpoint claim. This ensures that the wMaxPacketSize does not exceed the
> +	 * limit during bind retries where configured TX/RX FIFO's maxpacket size
> +	 * of 512 bytes for IN/OUT endpoints in support HS speed only.
> +	 */
> +	bulk_in_desc.wMaxPacketSize = cpu_to_le16(64);
> +	bulk_out_desc.wMaxPacketSize = cpu_to_le16(64);
> +
>   	/* allocate instance-specific endpoints */
>   	midi->in_ep = usb_ep_autoconfig(cdev->gadget, &bulk_in_desc);
>   	if (!midi->in_ep)

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Greg KH]

On Tue, Dec 10, 2024 at 03:23:22PM +0530, Selvarasu Ganesan wrote:
> Hello Maintainers.
> 
> Gentle remainder for review.

You sent this 2 days ago, right?

Please take the time to review other commits on the miailing list if you
wish to see your patches get reviewed faster, to help reduce the
workload of people reviewing your changes.

Otherwise just wait for people to get to it, what is the rush here?

thanks,

greg k-h

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/10/2024 3:48 PM, Greg KH wrote:
> On Tue, Dec 10, 2024 at 03:23:22PM +0530, Selvarasu Ganesan wrote:
>> Hello Maintainers.
>>
>> Gentle remainder for review.
> You sent this 2 days ago, right?
>
> Please take the time to review other commits on the miailing list if you
> wish to see your patches get reviewed faster, to help reduce the
> workload of people reviewing your changes.
>
> Otherwise just wait for people to get to it, what is the rush here?
>
> thanks,
>
> greg k-h


Hi Greg,


There is no rush. I understand that the review will take time and I 
apologize for any inconvenience caused by sending the reminder email.

Thanks,
Selva

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Greg KH]

On Tue, Dec 10, 2024 at 07:41:53PM +0530, Selvarasu Ganesan wrote:
> 
> On 12/10/2024 3:48 PM, Greg KH wrote:
> > On Tue, Dec 10, 2024 at 03:23:22PM +0530, Selvarasu Ganesan wrote:
> >> Hello Maintainers.
> >>
> >> Gentle remainder for review.
> > You sent this 2 days ago, right?
> >
> > Please take the time to review other commits on the miailing list if you
> > wish to see your patches get reviewed faster, to help reduce the
> > workload of people reviewing your changes.
> >
> > Otherwise just wait for people to get to it, what is the rush here?
> >
> > thanks,
> >
> > greg k-h
> 
> 
> Hi Greg,
> 
> 
> There is no rush. I understand that the review will take time and I 
> apologize for any inconvenience caused by sending the reminder email.

Great, during that time, please do some patch reviews of the changes on
the mailing list to help us out.

thanks,

greg k-h

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/10/2024 7:55 PM, Greg KH wrote:
> On Tue, Dec 10, 2024 at 07:41:53PM +0530, Selvarasu Ganesan wrote:
>> On 12/10/2024 3:48 PM, Greg KH wrote:
>>> On Tue, Dec 10, 2024 at 03:23:22PM +0530, Selvarasu Ganesan wrote:
>>>> Hello Maintainers.
>>>>
>>>> Gentle remainder for review.
>>> You sent this 2 days ago, right?
>>>
>>> Please take the time to review other commits on the miailing list if you
>>> wish to see your patches get reviewed faster, to help reduce the
>>> workload of people reviewing your changes.
>>>
>>> Otherwise just wait for people to get to it, what is the rush here?
>>>
>>> thanks,
>>>
>>> greg k-h
>>
>> Hi Greg,
>>
>>
>> There is no rush. I understand that the review will take time and I
>> apologize for any inconvenience caused by sending the reminder email.
> Great, during that time, please do some patch reviews of the changes on
> the mailing list to help us out.
>
> thanks,
>
> greg k-h

Hi Greg,

Sure, I will try to contribute on reviewing other patches.

Thanks,
Selva
>

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Greg KH]

On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
> The current implementation sets the wMaxPacketSize of bulk in/out
> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
> in cases where there is a failure in the first midi bind attempt,
> consider rebinding.

What considers rebinding?  Your change does not modify that.

> This scenario may encounter an f_midi_bind issue due
> to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024
> bytes, which exceeds the ep->maxpacket_limit where configured TX/RX
> FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS
> speed only.
> This commit addresses this issue by resetting the wMaxPacketSize before
> endpoint claim.

resets it to what?  Where did the magic numbers come from?  How do we
know this is now full speed and not high speed?

> 
> Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
> ---
>  drivers/usb/gadget/function/f_midi.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> index 837fcdfa3840..5caa0e4eb07e 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -907,6 +907,15 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
>  
>  	status = -ENODEV;
>  
> +	/*
> +	 * Reset wMaxPacketSize with maximum packet size of FS bulk transfer before
> +	 * endpoint claim. This ensures that the wMaxPacketSize does not exceed the
> +	 * limit during bind retries where configured TX/RX FIFO's maxpacket size
> +	 * of 512 bytes for IN/OUT endpoints in support HS speed only.
> +	 */
> +	bulk_in_desc.wMaxPacketSize = cpu_to_le16(64);
> +	bulk_out_desc.wMaxPacketSize = cpu_to_le16(64);

Where did "64" come from?  How do we know this is full speed?  Later
on in this function the endpoint sizes are set, why set them here to
these small values when you do not know the speed?

Or, if it had failed before, reset the values on the failure, not here
before you start anything up, right?

thanks,

greg k-h

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/18/2024 11:01 AM, Greg KH wrote:
> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
>> The current implementation sets the wMaxPacketSize of bulk in/out
>> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
>> in cases where there is a failure in the first midi bind attempt,
>> consider rebinding.
> What considers rebinding?  Your change does not modify that.

Hi Greg,
Thanks for your review comments.


Here the term "rebind" in this context refers to attempting to bind the 
MIDI function a second time in certain scenarios.
The situations where rebinding is considered include:

  * When there is a failure in the first UDC write attempt, which may be
    caused by other functions bind along with MIDI
  * Runtime composition change : Example : MIDI,ADB to MIDI. Or MIDI to
    MIDI,ADB

The issue arises during the second time the "f_midi_bind" function is 
called. The problem lies in the fact that the size of 
"bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call, 
which exceeds the hardware capability of the dwc3 TX/RX FIFO 
(ep->maxpacket_limit = 512).
Let consider the below sequence,


_1. First time f_midi_bind:_

  * As per the current codethe size of bulk_in_desc.wMaxPacketSize is 0
    in first time call.
  * Call usb_ep_autoconfig to match EP and got success as no failure in
    the below code as part of usb_ep_autoconfig.

    usb_gadget_ep_match_desc()
        {
        ..
        ..
        if (max > ep->maxpacket_limit)// (64 > 512)
            return 0;

        return 1;// Found Maching EP

        } 

  * EP claim got success and set bulk_in_desc.wMaxPacketSize =1024 at
    end of f_midi_bind.


_2. Second time enter into f_midi_bind _

  * The size of bulk_in_desc.wMaxPacketSize become 1024 because of above
    code.
  * Call usb_ep_autoconfig for EP claim and has a failure now in the
    below code as part of usb_ep_autoconfig

    usb_gadget_ep_match_desc()

    {
    ..
    ..
    if (max > ep->maxpacket_limit)// (1024 > 512)
    return 0; // Not found any matchingEP

    }


To resolve this issue, our patch sets the default value of 
"bulk_in_desc.wMaxPacketSize" to 64 before endpoint claim. This ensures 
that the endpoint claim is successful during the second time 
"f_midi_bind" is called.


>
>> This scenario may encounter an f_midi_bind issue due
>> to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024
>> bytes, which exceeds the ep->maxpacket_limit where configured TX/RX
>> FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS
>> speed only.
>> This commit addresses this issue by resetting the wMaxPacketSize before
>> endpoint claim.
> resets it to what?  Where did the magic numbers come from?  How do we
> know this is now full speed and not high speed?


It’s a generic way of setwMaxPacketSize before endpoint claim. Its 
because of the usb_ep_autoconfig treats endpoint descriptors as if they 
were full speed. This approach follows the same pattern as other 
function drivers, which also set the wMaxPacketSize to 64 before 
endpoint claim.

The following are the example of how other functions drivers EP claim.

_1. drivers/usb/gadget/function/f_eem.c_


eem_bind ()

{

…

..

/* allocate instance-specific endpoints */

ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc); 
//eem_fs_in_desc.wMaxPacketSize=64

if (!ep)

goto fail;

}

_2. drivers/usb/gadget/function/f_rndis.c_


rndis_bind()

{

...

...

/* allocate instance-specific endpoints */

ep = usb_ep_autoconfig(cdev->gadget, &fs_in_desc); 
//fs_in_desc.wMaxPacketSize=64

if (!ep)

goto fail;

rndis->port.in_ep = ep;

  }

Anyway the wMaxPacketSize set with 64 byte after complete 
usb_ep_autoconfig() as part of below this function ifep->maxpacket_limit 
is grater then 64. It's means treats endpoint descriptors as if they 
were full speed by default.

struct usb_ep *usb_ep_autoconfig()

{

..

…

if (type == USB_ENDPOINT_XFER_BULK) {

int size = ep->maxpacket_limit;

/* min() doesn't work on bitfields with gcc-3.5 */

if (size > 64)

size = 64;

desc->wMaxPacketSize = cpu_to_le16(size);

}

..

..

}

>> Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
>> ---
>>   drivers/usb/gadget/function/f_midi.c | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
>> index 837fcdfa3840..5caa0e4eb07e 100644
>> --- a/drivers/usb/gadget/function/f_midi.c
>> +++ b/drivers/usb/gadget/function/f_midi.c
>> @@ -907,6 +907,15 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
>>   
>>   	status = -ENODEV;
>>   
>> +	/*
>> +	 * Reset wMaxPacketSize with maximum packet size of FS bulk transfer before
>> +	 * endpoint claim. This ensures that the wMaxPacketSize does not exceed the
>> +	 * limit during bind retries where configured TX/RX FIFO's maxpacket size
>> +	 * of 512 bytes for IN/OUT endpoints in support HS speed only.
>> +	 */
>> +	bulk_in_desc.wMaxPacketSize = cpu_to_le16(64);
>> +	bulk_out_desc.wMaxPacketSize = cpu_to_le16(64);
> Where did "64" come from?  How do we know this is full speed?  Later
> on in this function the endpoint sizes are set, why set them here to
> these small values when you do not know the speed?
>
> Or, if it had failed before, reset the values on the failure, not here
> before you start anything up, right?

Explained as part of above ask.

>
> thanks,
>
> greg k-h
>

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Alan Stern]

On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
> The issue arises during the second time the "f_midi_bind" function is 
> called. The problem lies in the fact that the size of 
> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call, 
> which exceeds the hardware capability of the dwc3 TX/RX FIFO 
> (ep->maxpacket_limit = 512).

Is this gadget supposed to be able to run at SuperSpeed?  I thought the 
dwc3 controller supported SuperSpeed operation.

The USB-3 spec requires that all SuperSpeed bulk endpoints must have a 
wMaxPacketSize of 1024 (see Table 9-24 on p.9-25 of the USB-3.1 
specification).

Alan Stern

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/18/2024 9:21 PM, Alan Stern wrote:
> On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
>> The issue arises during the second time the "f_midi_bind" function is
>> called. The problem lies in the fact that the size of
>> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
>> which exceeds the hardware capability of the dwc3 TX/RX FIFO
>> (ep->maxpacket_limit = 512).
> Is this gadget supposed to be able to run at SuperSpeed?  I thought the
> dwc3 controller supported SuperSpeed operation.
>
> The USB-3 spec requires that all SuperSpeed bulk endpoints must have a
> wMaxPacketSize of 1024 (see Table 9-24 on p.9-25 of the USB-3.1
> specification).
>
> Alan Stern
>
Hi Alan,

No, In our platform, the DWC3 controller supports up to HighSpeed. While 
DWC3 is capable of SuperSpeed operation, it is not necessary to operate 
at the same speed. Moreover, even in our SoC, the DWC3 IP is limited to 
supporting only USB 2.0 mode (HighSpeed) at the hardware design level.

As previously mentioned, there is no need to set the wMaxPacketSize 
based on the current speed support before claiming the endpoint (before 
calling usb_ep_autoconfig), as usb_ep_autoconfig treats endpoint 
descriptors as if they were full-speed by default.

For reference, let's see the usb_ep_autoconfig code where the 
wMaxPacketSize is set to 64 bytes if the ep->maxpacket_limit is greater 
than 64. As i mentioned earlier in our specific failure scenarios, the 
code does not reach this point because the wMaxPacketSize is greater 
than the ep->maxpacket_limit.

struct usb_ep *usb_ep_autoconfig()
{
…
…
…
         /* report (variable) full speed bulk maxpacket */
         if (type == USB_ENDPOINT_XFER_BULK) {
                 int size = ep->maxpacket_limit;

                 if (size > 64)
                         size = 64;
                 desc->wMaxPacketSize = cpu_to_le16(size);
         }

         return ep;

}


Thanks,
Selva

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Greg KH]

On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
> 
> On 12/18/2024 11:01 AM, Greg KH wrote:
> > On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
> >> The current implementation sets the wMaxPacketSize of bulk in/out
> >> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
> >> in cases where there is a failure in the first midi bind attempt,
> >> consider rebinding.
> > What considers rebinding?  Your change does not modify that.
> 
> Hi Greg,
> Thanks for your review comments.
> 
> 
> Here the term "rebind" in this context refers to attempting to bind the 
> MIDI function a second time in certain scenarios.
> The situations where rebinding is considered include:
> 
>   * When there is a failure in the first UDC write attempt, which may be
>     caused by other functions bind along with MIDI
>   * Runtime composition change : Example : MIDI,ADB to MIDI. Or MIDI to
>     MIDI,ADB
> 
> The issue arises during the second time the "f_midi_bind" function is 
> called. The problem lies in the fact that the size of 
> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call, 
> which exceeds the hardware capability of the dwc3 TX/RX FIFO 
> (ep->maxpacket_limit = 512).

Ok, but then why not properly reset ALL of the options/values when a
failure happens, not just this one when the initialization happens
again?  Odds are you might be missing the change of something else here
as well, right?

Also, cleaning up from an error is a better thing to do than forcing
something to be set all the time when you don't have anything gone
wrong.

thanks,

greg k-h

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/20/2024 5:54 PM, Greg KH wrote:
> On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
>> On 12/18/2024 11:01 AM, Greg KH wrote:
>>> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
>>>> The current implementation sets the wMaxPacketSize of bulk in/out
>>>> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
>>>> in cases where there is a failure in the first midi bind attempt,
>>>> consider rebinding.
>>> What considers rebinding?  Your change does not modify that.
>> Hi Greg,
>> Thanks for your review comments.
>>
>>
>> Here the term "rebind" in this context refers to attempting to bind the
>> MIDI function a second time in certain scenarios.
>> The situations where rebinding is considered include:
>>
>>    * When there is a failure in the first UDC write attempt, which may be
>>      caused by other functions bind along with MIDI
>>    * Runtime composition change : Example : MIDI,ADB to MIDI. Or MIDI to
>>      MIDI,ADB
>>
>> The issue arises during the second time the "f_midi_bind" function is
>> called. The problem lies in the fact that the size of
>> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
>> which exceeds the hardware capability of the dwc3 TX/RX FIFO
>> (ep->maxpacket_limit = 512).
> Ok, but then why not properly reset ALL of the options/values when a
> failure happens, not just this one when the initialization happens
> again?  Odds are you might be missing the change of something else here
> as well, right?
Are you suggesting that we reset the entire value of 
usb_endpoint_descriptor before call usb_ep_autoconfig? If so, Sorry I am 
not clear on your reasoning for wanting to reset all options/values. 
After all, all values will be overwritten 
afterusb_ep_autoconfig.Additionally, the wMaxPacketSize is the only 
value being checked during the EP claim process (usb_ep_autoconfig), and 
it has caused issues where claiming wMaxPacketSize is grater than 
ep->maxpacket_limit.
>
> Also, cleaning up from an error is a better thing to do than forcing
> something to be set all the time when you don't have anything gone
> wrong.
As I previously mentioned, this is a general approach to set 
wMaxPacketSize before claiming the endpoint. This is because the 
usb_ep_autoconfig treats endpoint descriptors as if they were full 
speed. Following the same pattern as other function drivers, that 
approach allows us to claim the EP with using a full-speed descriptor. 
We can use the same approach here instead of resetting wMaxPacketSize 
every time.

The following provided code is used to claim an EP with a full-speed 
bulk descriptor in MIDI. Its also working solution.  But, We thinking 
that it may unnecessarily complicate the code as it only utilizes the 
full descriptor for obtaining the EP address here. What you think shall 
we go with below approach instead of rest wMaxPacketSize before call 
usb_ep_autoconfig?

diff --git a/drivers/usb/gadget/function/f_midi.c 
b/drivers/usb/gadget/function/f_midi.c
index 837fcdfa3840..fe12c8d82bf2 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -116,6 +116,22 @@ DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);
  DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
  DECLARE_USB_MS_ENDPOINT_DESCRIPTOR(16);

+static struct usb_endpoint_descriptor fs_bulk_in_desc = {
+ .bLength =              USB_DT_ENDPOINT_SIZE,
+ .bDescriptorType =      USB_DT_ENDPOINT,
+
+ .bEndpointAddress =     USB_DIR_IN,
+ .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor fs_bulk_out_desc = {
+ .bLength =              USB_DT_ENDPOINT_SIZE,
+ .bDescriptorType =      USB_DT_ENDPOINT,
+
+ .bEndpointAddress =     USB_DIR_OUT,
+ .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+};
+
  /* B.3.1  Standard AC Interface Descriptor */
  static struct usb_interface_descriptor ac_interface_desc = {
.bLength =              USB_DT_INTERFACE_SIZE,
@@ -908,11 +924,11 @@ static int f_midi_bind(struct usb_configuration 
*c, struct usb_function *f)
status = -ENODEV;

/* allocate instance-specific endpoints */
- midi->in_ep = usb_ep_autoconfig(cdev->gadget, &bulk_in_desc);
+ midi->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_bulk_in_desc);
if (!midi->in_ep)
goto fail;

- midi->out_ep = usb_ep_autoconfig(cdev->gadget, &bulk_out_desc);
+ midi->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_bulk_out_desc);
if (!midi->out_ep)
goto fail;

@@ -1006,6 +1022,9 @@ static int f_midi_bind(struct usb_configuration 
*c, struct usb_function *f)
ms_in_desc.bLength = USB_DT_MS_ENDPOINT_SIZE(midi->out_ports);
ms_in_desc.bNumEmbMIDIJack = midi->out_ports;

+ bulk_in_desc.bEndpointAddress = fs_bulk_in_desc.bEndpointAddress;
+ bulk_out_desc.bEndpointAddress = fs_bulk_out_desc.bEndpointAddress;
+
/* ... and add them to the list */
endpoint_descriptor_index = i;
midi_function[i++] = (struct usb_descriptor_header *) &bulk_out_desc;



>
> thanks,
>
> greg k-h
>

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Greg KH]

On Fri, Dec 20, 2024 at 07:02:06PM +0530, Selvarasu Ganesan wrote:
> 
> On 12/20/2024 5:54 PM, Greg KH wrote:
> > On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
> >> On 12/18/2024 11:01 AM, Greg KH wrote:
> >>> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
> >>>> The current implementation sets the wMaxPacketSize of bulk in/out
> >>>> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
> >>>> in cases where there is a failure in the first midi bind attempt,
> >>>> consider rebinding.
> >>> What considers rebinding?  Your change does not modify that.
> >> Hi Greg,
> >> Thanks for your review comments.
> >>
> >>
> >> Here the term "rebind" in this context refers to attempting to bind the
> >> MIDI function a second time in certain scenarios.
> >> The situations where rebinding is considered include:
> >>
> >>    * When there is a failure in the first UDC write attempt, which may be
> >>      caused by other functions bind along with MIDI
> >>    * Runtime composition change : Example : MIDI,ADB to MIDI. Or MIDI to
> >>      MIDI,ADB
> >>
> >> The issue arises during the second time the "f_midi_bind" function is
> >> called. The problem lies in the fact that the size of
> >> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
> >> which exceeds the hardware capability of the dwc3 TX/RX FIFO
> >> (ep->maxpacket_limit = 512).
> > Ok, but then why not properly reset ALL of the options/values when a
> > failure happens, not just this one when the initialization happens
> > again?  Odds are you might be missing the change of something else here
> > as well, right?
> Are you suggesting that we reset the entire value of 
> usb_endpoint_descriptor before call usb_ep_autoconfig? If so, Sorry I am 
> not clear on your reasoning for wanting to reset all options/values. 
> After all, all values will be overwritten 
> afterusb_ep_autoconfig.Additionally, the wMaxPacketSize is the only 
> value being checked during the EP claim process (usb_ep_autoconfig), and 
> it has caused issues where claiming wMaxPacketSize is grater than 
> ep->maxpacket_limit.

Then fix up that value on failure, if things fail you should reset it
back to a "known good state", right?  And what's wrong with resetting
all of the values anyway, wouldn't that be the correct thing to do?

> > Also, cleaning up from an error is a better thing to do than forcing
> > something to be set all the time when you don't have anything gone
> > wrong.
> As I previously mentioned, this is a general approach to set 
> wMaxPacketSize before claiming the endpoint. This is because the 
> usb_ep_autoconfig treats endpoint descriptors as if they were full 
> speed. Following the same pattern as other function drivers, that 
> approach allows us to claim the EP with using a full-speed descriptor. 
> We can use the same approach here instead of resetting wMaxPacketSize 
> every time.
> 
> The following provided code is used to claim an EP with a full-speed 
> bulk descriptor in MIDI. Its also working solution.  But, We thinking 
> that it may unnecessarily complicate the code as it only utilizes the 
> full descriptor for obtaining the EP address here. What you think shall 
> we go with below approach instead of rest wMaxPacketSize before call 
> usb_ep_autoconfig?

I don't know, what do you think is best to do?  You are the one having
problems and will need to fix any bugs that your changes will cause :)

thanks,

greg k-h

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/20/2024 8:45 PM, Greg KH wrote:
> On Fri, Dec 20, 2024 at 07:02:06PM +0530, Selvarasu Ganesan wrote:
>> On 12/20/2024 5:54 PM, Greg KH wrote:
>>> On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
>>>> On 12/18/2024 11:01 AM, Greg KH wrote:
>>>>> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
>>>>>> The current implementation sets the wMaxPacketSize of bulk in/out
>>>>>> endpoints to 1024 bytes at the end of the f_midi_bind function. However,
>>>>>> in cases where there is a failure in the first midi bind attempt,
>>>>>> consider rebinding.
>>>>> What considers rebinding?  Your change does not modify that.
>>>> Hi Greg,
>>>> Thanks for your review comments.
>>>>
>>>>
>>>> Here the term "rebind" in this context refers to attempting to bind the
>>>> MIDI function a second time in certain scenarios.
>>>> The situations where rebinding is considered include:
>>>>
>>>>     * When there is a failure in the first UDC write attempt, which may be
>>>>       caused by other functions bind along with MIDI
>>>>     * Runtime composition change : Example : MIDI,ADB to MIDI. Or MIDI to
>>>>       MIDI,ADB
>>>>
>>>> The issue arises during the second time the "f_midi_bind" function is
>>>> called. The problem lies in the fact that the size of
>>>> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
>>>> which exceeds the hardware capability of the dwc3 TX/RX FIFO
>>>> (ep->maxpacket_limit = 512).
>>> Ok, but then why not properly reset ALL of the options/values when a
>>> failure happens, not just this one when the initialization happens
>>> again?  Odds are you might be missing the change of something else here
>>> as well, right?
>> Are you suggesting that we reset the entire value of
>> usb_endpoint_descriptor before call usb_ep_autoconfig? If so, Sorry I am
>> not clear on your reasoning for wanting to reset all options/values.
>> After all, all values will be overwritten
>> afterusb_ep_autoconfig.Additionally, the wMaxPacketSize is the only
>> value being checked during the EP claim process (usb_ep_autoconfig), and
>> it has caused issues where claiming wMaxPacketSize is grater than
>> ep->maxpacket_limit.
> Then fix up that value on failure, if things fail you should reset it
> back to a "known good state", right?  And what's wrong with resetting
> all of the values anyway, wouldn't that be the correct thing to do?

Yes, It's back to known good state if we reset wMaxPacketSize. There is 
no point to reset all values in the usb endpoint descriptor structure as 
all the member of this structure are predefined value except 
wMaxPacketSize and bEndpointAddress. The bEndpointAddress is obtain as 
part of usb_ep_autoconfig.

static struct usb_endpoint_descriptor bulk_out_desc = {
         .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
         .bDescriptorType =      USB_DT_ENDPOINT,
         .bEndpointAddress =     USB_DIR_OUT,
         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

>>> Also, cleaning up from an error is a better thing to do than forcing
>>> something to be set all the time when you don't have anything gone
>>> wrong.
>> As I previously mentioned, this is a general approach to set
>> wMaxPacketSize before claiming the endpoint. This is because the
>> usb_ep_autoconfig treats endpoint descriptors as if they were full
>> speed. Following the same pattern as other function drivers, that
>> approach allows us to claim the EP with using a full-speed descriptor.
>> We can use the same approach here instead of resetting wMaxPacketSize
>> every time.
>>
>> The following provided code is used to claim an EP with a full-speed
>> bulk descriptor in MIDI. Its also working solution.  But, We thinking
>> that it may unnecessarily complicate the code as it only utilizes the
>> full descriptor for obtaining the EP address here. What you think shall
>> we go with below approach instead of rest wMaxPacketSize before call
>> usb_ep_autoconfig?
> I don't know, what do you think is best to do?  You are the one having
> problems and will need to fix any bugs that your changes will cause :)
>
> thanks,
>
> greg k-h

We agree. Restting wMaxPacketSize is the best solution for this issue, 
as concluded from our internal review meeting as well.

Thanks,
Selva

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/21/2024 11:37 PM, Selvarasu Ganesan wrote:
>
> On 12/20/2024 8:45 PM, Greg KH wrote:
>> On Fri, Dec 20, 2024 at 07:02:06PM +0530, Selvarasu Ganesan wrote:
>>> On 12/20/2024 5:54 PM, Greg KH wrote:
>>>> On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
>>>>> On 12/18/2024 11:01 AM, Greg KH wrote:
>>>>>> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
>>>>>>> The current implementation sets the wMaxPacketSize of bulk in/out
>>>>>>> endpoints to 1024 bytes at the end of the f_midi_bind function. 
>>>>>>> However,
>>>>>>> in cases where there is a failure in the first midi bind attempt,
>>>>>>> consider rebinding.
>>>>>> What considers rebinding?  Your change does not modify that.
>>>>> Hi Greg,
>>>>> Thanks for your review comments.
>>>>>
>>>>>
>>>>> Here the term "rebind" in this context refers to attempting to 
>>>>> bind the
>>>>> MIDI function a second time in certain scenarios.
>>>>> The situations where rebinding is considered include:
>>>>>
>>>>>     * When there is a failure in the first UDC write attempt, 
>>>>> which may be
>>>>>       caused by other functions bind along with MIDI
>>>>>     * Runtime composition change : Example : MIDI,ADB to MIDI. Or 
>>>>> MIDI to
>>>>>       MIDI,ADB
>>>>>
>>>>> The issue arises during the second time the "f_midi_bind" function is
>>>>> called. The problem lies in the fact that the size of
>>>>> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
>>>>> which exceeds the hardware capability of the dwc3 TX/RX FIFO
>>>>> (ep->maxpacket_limit = 512).
>>>> Ok, but then why not properly reset ALL of the options/values when a
>>>> failure happens, not just this one when the initialization happens
>>>> again?  Odds are you might be missing the change of something else 
>>>> here
>>>> as well, right?
>>> Are you suggesting that we reset the entire value of
>>> usb_endpoint_descriptor before call usb_ep_autoconfig? If so, Sorry 
>>> I am
>>> not clear on your reasoning for wanting to reset all options/values.
>>> After all, all values will be overwritten
>>> afterusb_ep_autoconfig.Additionally, the wMaxPacketSize is the only
>>> value being checked during the EP claim process (usb_ep_autoconfig), 
>>> and
>>> it has caused issues where claiming wMaxPacketSize is grater than
>>> ep->maxpacket_limit.
>> Then fix up that value on failure, if things fail you should reset it
>> back to a "known good state", right?  And what's wrong with resetting
>> all of the values anyway, wouldn't that be the correct thing to do?
>
> Yes, It's back to known good state if we reset wMaxPacketSize. There 
> is no point to reset all values in the usb endpoint descriptor 
> structure as all the member of this structure are predefined value 
> except wMaxPacketSize and bEndpointAddress. The bEndpointAddress is 
> obtain as part of usb_ep_autoconfig.
>
> static struct usb_endpoint_descriptor bulk_out_desc = {
>         .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
>         .bDescriptorType =      USB_DT_ENDPOINT,
>         .bEndpointAddress =     USB_DIR_OUT,
>         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
> };
>
>>>> Also, cleaning up from an error is a better thing to do than forcing
>>>> something to be set all the time when you don't have anything gone
>>>> wrong.
>>> As I previously mentioned, this is a general approach to set
>>> wMaxPacketSize before claiming the endpoint. This is because the
>>> usb_ep_autoconfig treats endpoint descriptors as if they were full
>>> speed. Following the same pattern as other function drivers, that
>>> approach allows us to claim the EP with using a full-speed descriptor.
>>> We can use the same approach here instead of resetting wMaxPacketSize
>>> every time.
>>>
>>> The following provided code is used to claim an EP with a full-speed
>>> bulk descriptor in MIDI. Its also working solution.  But, We thinking
>>> that it may unnecessarily complicate the code as it only utilizes the
>>> full descriptor for obtaining the EP address here. What you think shall
>>> we go with below approach instead of rest wMaxPacketSize before call
>>> usb_ep_autoconfig?
>> I don't know, what do you think is best to do?  You are the one having
>> problems and will need to fix any bugs that your changes will cause :)
>>
>> thanks,
>>
>> greg k-h
>
> We agree. Restting wMaxPacketSize is the best solution for this issue, 
> as concluded from our internal review meeting as well.
>
> Thanks,
> Selva


Hi Greg,

Do you have any suggestions or further comments on this?.

Thanks,
Selva

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 12/21/2024 11:37 PM, Selvarasu Ganesan wrote:
>
> On 12/20/2024 8:45 PM, Greg KH wrote:
>> On Fri, Dec 20, 2024 at 07:02:06PM +0530, Selvarasu Ganesan wrote:
>>> On 12/20/2024 5:54 PM, Greg KH wrote:
>>>> On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
>>>>> On 12/18/2024 11:01 AM, Greg KH wrote:
>>>>>> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
>>>>>>> The current implementation sets the wMaxPacketSize of bulk in/out
>>>>>>> endpoints to 1024 bytes at the end of the f_midi_bind function. 
>>>>>>> However,
>>>>>>> in cases where there is a failure in the first midi bind attempt,
>>>>>>> consider rebinding.
>>>>>> What considers rebinding?  Your change does not modify that.
>>>>> Hi Greg,
>>>>> Thanks for your review comments.
>>>>>
>>>>>
>>>>> Here the term "rebind" in this context refers to attempting to 
>>>>> bind the
>>>>> MIDI function a second time in certain scenarios.
>>>>> The situations where rebinding is considered include:
>>>>>
>>>>>     * When there is a failure in the first UDC write attempt, 
>>>>> which may be
>>>>>       caused by other functions bind along with MIDI
>>>>>     * Runtime composition change : Example : MIDI,ADB to MIDI. Or 
>>>>> MIDI to
>>>>>       MIDI,ADB
>>>>>
>>>>> The issue arises during the second time the "f_midi_bind" function is
>>>>> called. The problem lies in the fact that the size of
>>>>> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
>>>>> which exceeds the hardware capability of the dwc3 TX/RX FIFO
>>>>> (ep->maxpacket_limit = 512).
>>>> Ok, but then why not properly reset ALL of the options/values when a
>>>> failure happens, not just this one when the initialization happens
>>>> again?  Odds are you might be missing the change of something else 
>>>> here
>>>> as well, right?
>>> Are you suggesting that we reset the entire value of
>>> usb_endpoint_descriptor before call usb_ep_autoconfig? If so, Sorry 
>>> I am
>>> not clear on your reasoning for wanting to reset all options/values.
>>> After all, all values will be overwritten
>>> afterusb_ep_autoconfig.Additionally, the wMaxPacketSize is the only
>>> value being checked during the EP claim process (usb_ep_autoconfig), 
>>> and
>>> it has caused issues where claiming wMaxPacketSize is grater than
>>> ep->maxpacket_limit.
>> Then fix up that value on failure, if things fail you should reset it
>> back to a "known good state", right?  And what's wrong with resetting
>> all of the values anyway, wouldn't that be the correct thing to do?
>
> Yes, It's back to known good state if we reset wMaxPacketSize. There 
> is no point to reset all values in the usb endpoint descriptor 
> structure as all the member of this structure are predefined value 
> except wMaxPacketSize and bEndpointAddress. The bEndpointAddress is 
> obtain as part of usb_ep_autoconfig.
>
> static struct usb_endpoint_descriptor bulk_out_desc = {
>         .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
>         .bDescriptorType =      USB_DT_ENDPOINT,
>         .bEndpointAddress =     USB_DIR_OUT,
>         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
> };
>
HI Greg,

Gentle remainder for your further comments or suggestions on this.

Thanks,
Selva

>>>> Also, cleaning up from an error is a better thing to do than forcing
>>>> something to be set all the time when you don't have anything gone
>>>> wrong.
>>> As I previously mentioned, this is a general approach to set
>>> wMaxPacketSize before claiming the endpoint. This is because the
>>> usb_ep_autoconfig treats endpoint descriptors as if they were full
>>> speed. Following the same pattern as other function drivers, that
>>> approach allows us to claim the EP with using a full-speed descriptor.
>>> We can use the same approach here instead of resetting wMaxPacketSize
>>> every time.
>>>
>>> The following provided code is used to claim an EP with a full-speed
>>> bulk descriptor in MIDI. Its also working solution.  But, We thinking
>>> that it may unnecessarily complicate the code as it only utilizes the
>>> full descriptor for obtaining the EP address here. What you think shall
>>> we go with below approach instead of rest wMaxPacketSize before call
>>> usb_ep_autoconfig?
>> I don't know, what do you think is best to do?  You are the one having
>> problems and will need to fix any bugs that your changes will cause :)
>>
>> thanks,
>>
>> greg k-h
>
> We agree. Restting wMaxPacketSize is the best solution for this issue, 
> as concluded from our internal review meeting as well.
>
> Thanks,
> Selva

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Greg KH]

On Thu, Jan 16, 2025 at 10:49:24AM +0530, Selvarasu Ganesan wrote:
> 
> On 12/21/2024 11:37 PM, Selvarasu Ganesan wrote:
> >
> > On 12/20/2024 8:45 PM, Greg KH wrote:
> >> On Fri, Dec 20, 2024 at 07:02:06PM +0530, Selvarasu Ganesan wrote:
> >>> On 12/20/2024 5:54 PM, Greg KH wrote:
> >>>> On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
> >>>>> On 12/18/2024 11:01 AM, Greg KH wrote:
> >>>>>> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
> >>>>>>> The current implementation sets the wMaxPacketSize of bulk in/out
> >>>>>>> endpoints to 1024 bytes at the end of the f_midi_bind function. 
> >>>>>>> However,
> >>>>>>> in cases where there is a failure in the first midi bind attempt,
> >>>>>>> consider rebinding.
> >>>>>> What considers rebinding?  Your change does not modify that.
> >>>>> Hi Greg,
> >>>>> Thanks for your review comments.
> >>>>>
> >>>>>
> >>>>> Here the term "rebind" in this context refers to attempting to 
> >>>>> bind the
> >>>>> MIDI function a second time in certain scenarios.
> >>>>> The situations where rebinding is considered include:
> >>>>>
> >>>>>     * When there is a failure in the first UDC write attempt, 
> >>>>> which may be
> >>>>>       caused by other functions bind along with MIDI
> >>>>>     * Runtime composition change : Example : MIDI,ADB to MIDI. Or 
> >>>>> MIDI to
> >>>>>       MIDI,ADB
> >>>>>
> >>>>> The issue arises during the second time the "f_midi_bind" function is
> >>>>> called. The problem lies in the fact that the size of
> >>>>> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
> >>>>> which exceeds the hardware capability of the dwc3 TX/RX FIFO
> >>>>> (ep->maxpacket_limit = 512).
> >>>> Ok, but then why not properly reset ALL of the options/values when a
> >>>> failure happens, not just this one when the initialization happens
> >>>> again?  Odds are you might be missing the change of something else 
> >>>> here
> >>>> as well, right?
> >>> Are you suggesting that we reset the entire value of
> >>> usb_endpoint_descriptor before call usb_ep_autoconfig? If so, Sorry 
> >>> I am
> >>> not clear on your reasoning for wanting to reset all options/values.
> >>> After all, all values will be overwritten
> >>> afterusb_ep_autoconfig.Additionally, the wMaxPacketSize is the only
> >>> value being checked during the EP claim process (usb_ep_autoconfig), 
> >>> and
> >>> it has caused issues where claiming wMaxPacketSize is grater than
> >>> ep->maxpacket_limit.
> >> Then fix up that value on failure, if things fail you should reset it
> >> back to a "known good state", right?  And what's wrong with resetting
> >> all of the values anyway, wouldn't that be the correct thing to do?
> >
> > Yes, It's back to known good state if we reset wMaxPacketSize. There 
> > is no point to reset all values in the usb endpoint descriptor 
> > structure as all the member of this structure are predefined value 
> > except wMaxPacketSize and bEndpointAddress. The bEndpointAddress is 
> > obtain as part of usb_ep_autoconfig.
> >
> > static struct usb_endpoint_descriptor bulk_out_desc = {
> >         .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
> >         .bDescriptorType =      USB_DT_ENDPOINT,
> >         .bEndpointAddress =     USB_DIR_OUT,
> >         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
> > };
> >
> HI Greg,
> 
> Gentle remainder for your further comments or suggestions on this.

Sorry, I don't remember, it was thousands of patches reviewed ago.  If
you feel your submission was correct, and no changes are needed, resend
with an expanded changelog text to help explain things so I don't have
the same questions again.

thanks,

greg k-h

Re: [PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

[Selvarasu Ganesan]

On 1/17/2025 4:35 PM, Greg KH wrote:
> On Thu, Jan 16, 2025 at 10:49:24AM +0530, Selvarasu Ganesan wrote:
>> On 12/21/2024 11:37 PM, Selvarasu Ganesan wrote:
>>> On 12/20/2024 8:45 PM, Greg KH wrote:
>>>> On Fri, Dec 20, 2024 at 07:02:06PM +0530, Selvarasu Ganesan wrote:
>>>>> On 12/20/2024 5:54 PM, Greg KH wrote:
>>>>>> On Wed, Dec 18, 2024 at 03:51:50PM +0530, Selvarasu Ganesan wrote:
>>>>>>> On 12/18/2024 11:01 AM, Greg KH wrote:
>>>>>>>> On Sun, Dec 08, 2024 at 08:53:20PM +0530, Selvarasu Ganesan wrote:
>>>>>>>>> The current implementation sets the wMaxPacketSize of bulk in/out
>>>>>>>>> endpoints to 1024 bytes at the end of the f_midi_bind function.
>>>>>>>>> However,
>>>>>>>>> in cases where there is a failure in the first midi bind attempt,
>>>>>>>>> consider rebinding.
>>>>>>>> What considers rebinding?  Your change does not modify that.
>>>>>>> Hi Greg,
>>>>>>> Thanks for your review comments.
>>>>>>>
>>>>>>>
>>>>>>> Here the term "rebind" in this context refers to attempting to
>>>>>>> bind the
>>>>>>> MIDI function a second time in certain scenarios.
>>>>>>> The situations where rebinding is considered include:
>>>>>>>
>>>>>>>      * When there is a failure in the first UDC write attempt,
>>>>>>> which may be
>>>>>>>        caused by other functions bind along with MIDI
>>>>>>>      * Runtime composition change : Example : MIDI,ADB to MIDI. Or
>>>>>>> MIDI to
>>>>>>>        MIDI,ADB
>>>>>>>
>>>>>>> The issue arises during the second time the "f_midi_bind" function is
>>>>>>> called. The problem lies in the fact that the size of
>>>>>>> "bulk_in_desc.wMaxPacketSize" is set to 1024 during the first call,
>>>>>>> which exceeds the hardware capability of the dwc3 TX/RX FIFO
>>>>>>> (ep->maxpacket_limit = 512).
>>>>>> Ok, but then why not properly reset ALL of the options/values when a
>>>>>> failure happens, not just this one when the initialization happens
>>>>>> again?  Odds are you might be missing the change of something else
>>>>>> here
>>>>>> as well, right?
>>>>> Are you suggesting that we reset the entire value of
>>>>> usb_endpoint_descriptor before call usb_ep_autoconfig? If so, Sorry
>>>>> I am
>>>>> not clear on your reasoning for wanting to reset all options/values.
>>>>> After all, all values will be overwritten
>>>>> afterusb_ep_autoconfig.Additionally, the wMaxPacketSize is the only
>>>>> value being checked during the EP claim process (usb_ep_autoconfig),
>>>>> and
>>>>> it has caused issues where claiming wMaxPacketSize is grater than
>>>>> ep->maxpacket_limit.
>>>> Then fix up that value on failure, if things fail you should reset it
>>>> back to a "known good state", right?  And what's wrong with resetting
>>>> all of the values anyway, wouldn't that be the correct thing to do?
>>> Yes, It's back to known good state if we reset wMaxPacketSize. There
>>> is no point to reset all values in the usb endpoint descriptor
>>> structure as all the member of this structure are predefined value
>>> except wMaxPacketSize and bEndpointAddress. The bEndpointAddress is
>>> obtain as part of usb_ep_autoconfig.
>>>
>>> static struct usb_endpoint_descriptor bulk_out_desc = {
>>>          .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
>>>          .bDescriptorType =      USB_DT_ENDPOINT,
>>>          .bEndpointAddress =     USB_DIR_OUT,
>>>          .bmAttributes =         USB_ENDPOINT_XFER_BULK,
>>> };
>>>
>> HI Greg,
>>
>> Gentle remainder for your further comments or suggestions on this.
> Sorry, I don't remember, it was thousands of patches reviewed ago.  If
> you feel your submission was correct, and no changes are needed, resend
> with an expanded changelog text to help explain things so I don't have
> the same questions again.
>
> thanks,
>
> greg k-h

Hi Greg,

I understand. Thanks for your update.

Yes, no changes are needed. I updated new version with expanded 
changelog in below link.

https://lore.kernel.org/all/20250118060134.927-1-selvarasu.g@samsung.com/

Thanks,
Selva
>