2023-02-06 22:13:07

by Bastien Nocera

Subject: [PATCH v2 2/3] HID: logitech-hidpp: Retry commands when device is busy

Handle the busy error coming from the device or receiver. The
documentation says a busy error can be returned when:
"
Device (or receiver) cannot answer immediately to this request
for any reason i.e:
- already processing a request from the same or another SW
- pipe full
"

Signed-off-by: Bastien Nocera <[email protected]>
---

Same as v1

drivers/hid/hid-logitech-hidpp.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 1952d8d3b6b2..9e94026de437 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -295,6 +295,7 @@ static int hidpp_send_message_sync(struct hidpp_device *hidpp,
*/
*response = *message;

+retry:
ret = __hidpp_send_report(hidpp->hid_dev, message);

if (ret) {
@@ -321,6 +322,10 @@ static int hidpp_send_message_sync(struct hidpp_device *hidpp,
response->report_id == REPORT_ID_HIDPP_VERY_LONG) &&
response->fap.feature_index == HIDPP20_ERROR) {
ret = response->fap.params[1];
+ if (ret == HIDPP20_ERROR_BUSY) {
+ dbg_hid("%s:got busy hidpp 2.0 error %02X, retrying\n", __func__, ret);
+ goto retry;
+ }
dbg_hid("%s:got hidpp 2.0 error %02X\n", __func__, ret);
goto exit;
}
--
2.39.1

2023-02-09 14:51:55

by Benjamin Tissoires

Subject: Re: [PATCH v2 2/3] HID: logitech-hidpp: Retry commands when device is busy

On Feb 06 2023, Bastien Nocera wrote:
> Handle the busy error coming from the device or receiver. The
> documentation says a busy error can be returned when:
> "
> Device (or receiver) cannot answer immediately to this request
> for any reason i.e:
> - already processing a request from the same or another SW
> - pipe full
> "
>
> Signed-off-by: Bastien Nocera <[email protected]>
> ---
>
> Same as v1
>
> drivers/hid/hid-logitech-hidpp.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> index 1952d8d3b6b2..9e94026de437 100644
> --- a/drivers/hid/hid-logitech-hidpp.c
> +++ b/drivers/hid/hid-logitech-hidpp.c
> @@ -295,6 +295,7 @@ static int hidpp_send_message_sync(struct hidpp_device *hidpp,
> */
> *response = *message;
>
> +retry:
> ret = __hidpp_send_report(hidpp->hid_dev, message);
>
> if (ret) {
> @@ -321,6 +322,10 @@ static int hidpp_send_message_sync(struct hidpp_device *hidpp,
> response->report_id == REPORT_ID_HIDPP_VERY_LONG) &&
> response->fap.feature_index == HIDPP20_ERROR) {
> ret = response->fap.params[1];
> + if (ret == HIDPP20_ERROR_BUSY) {
> + dbg_hid("%s:got busy hidpp 2.0 error %02X, retrying\n", __func__, ret);
> + goto retry;

I must confess, I blocked a little bit there to decide whether or not
using goto here was OK.

But then I reliazed that there is no way to leave that function if the
device is buggy and constantly sends back ERROR_BUSY. So I am not very
found of the idea of having that got after all.

Would you mind respinning that patch with a bounded loop for the retries
instead of using a goto? I'd like the driver to give up after a few
retries if the device is not fair.

Cheers,
Benjamin

> + }
> dbg_hid("%s:got hidpp 2.0 error %02X\n", __func__, ret);
> goto exit;
> }
> --
> 2.39.1
>

2023-02-09 15:50:51

by Bastien Nocera

Subject: Re: [PATCH v2 2/3] HID: logitech-hidpp: Retry commands when device is busy

On Thu, 2023-02-09 at 15:50 +0100, Benjamin Tissoires wrote:
> On Feb 06 2023, Bastien Nocera wrote:
> > Handle the busy error coming from the device or receiver. The
> > documentation says a busy error can be returned when:
> > "
> > Device (or receiver) cannot answer immediately to this request
> > for any reason i.e:
> > - already processing a request from the same or another SW
> > - pipe full
> > "
> >
> > Signed-off-by: Bastien Nocera <[email protected]>
> > ---
> >
> > Same as v1
> >
> >  drivers/hid/hid-logitech-hidpp.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-
> > logitech-hidpp.c
> > index 1952d8d3b6b2..9e94026de437 100644
> > --- a/drivers/hid/hid-logitech-hidpp.c
> > +++ b/drivers/hid/hid-logitech-hidpp.c
> > @@ -295,6 +295,7 @@ static int hidpp_send_message_sync(struct
> > hidpp_device *hidpp,
> >          */
> >         *response = *message;
> >  
> > +retry:
> >         ret = __hidpp_send_report(hidpp->hid_dev, message);
> >  
> >         if (ret) {
> > @@ -321,6 +322,10 @@ static int hidpp_send_message_sync(struct
> > hidpp_device *hidpp,
> >                         response->report_id ==
> > REPORT_ID_HIDPP_VERY_LONG) &&
> >                         response->fap.feature_index ==
> > HIDPP20_ERROR) {
> >                 ret = response->fap.params[1];
> > +               if (ret == HIDPP20_ERROR_BUSY) {
> > +                       dbg_hid("%s:got busy hidpp 2.0 error %02X,
> > retrying\n", __func__, ret);
> > +                       goto retry;
>
> I must confess, I blocked a little bit there to decide whether or not
> using goto here was OK.
>
> But then I reliazed that there is no way to leave that function if
> the
> device is buggy and constantly sends back ERROR_BUSY. So I am not
> very
> found of the idea of having that got after all.
>
> Would you mind respinning that patch with a bounded loop for the
> retries
> instead of using a goto? I'd like the driver to give up after a few
> retries if the device is not fair.

Done in v3.