linux-kernel - Re: [PATCH] HID: i2c-hid: Stop querying for init reports

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Message-ID: <CAN+gG=FukmZEpo8wvsmNeV=0h7xR9xYOPLyvYEiDq98T-4tn=A@mail.gmail.com>
Date:	Thu, 17 Oct 2013 13:57:04 -0400
From:	Benjamin Tissoires <benjamin.tissoires@...il.com>
To:	Bibek Basu <bbasu@...dia.com>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	linux-input <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] HID: i2c-hid: Stop querying for init reports

Hi Bibek,

On Tue, Oct 15, 2013 at 4:28 AM, Bibek Basu <bbasu@...dia.com> wrote:
> According to specifications, HID over I2C devices
> are not bound to respond to query for INPUT
> REPORTS. Thus dropping the call during init
> as many devices does not respond causing error
> messages during boot.
>

This time, the patch is removing too many things that are correct. :)

see below to know what to remove and what to keep:

> Signed-off-by: Bibek Basu <bbasu@...dia.com>
> ---
>  drivers/hid/i2c-hid/i2c-hid.c | 59 -------------------------------------------
>  1 file changed, 59 deletions(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index fd7ce37..58a4f12 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -409,62 +409,6 @@ static int i2c_hid_get_report_length(struct hid_report *report)
>                 report->device->report_enum[report->type].numbered + 2;
>  }
>
> -static void i2c_hid_init_report(struct hid_report *report, u8 *buffer,
> -       size_t bufsize)
> -{
> -       struct hid_device *hid = report->device;
> -       struct i2c_client *client = hid->driver_data;
> -       struct i2c_hid *ihid = i2c_get_clientdata(client);
> -       unsigned int size, ret_size;
> -
> -       size = i2c_hid_get_report_length(report);
> -       if (i2c_hid_get_report(client,
> -                       report->type == HID_FEATURE_REPORT ? 0x03 : 0x01,
> -                       report->id, buffer, size))
> -               return;
> -
> -       i2c_hid_dbg(ihid, "report (len=%d): %*ph\n", size, size, ihid->inbuf);
> -
> -       ret_size = buffer[0] | (buffer[1] << 8);
> -
> -       if (ret_size != size) {
> -               dev_err(&client->dev, "error in %s size:%d / ret_size:%d\n",
> -                       __func__, size, ret_size);
> -               return;
> -       }
> -
> -       /* hid->driver_lock is held as we are in probe function,
> -        * we just need to setup the input fields, so using
> -        * hid_report_raw_event is safe. */
> -       hid_report_raw_event(hid, report->type, buffer + 2, size - 2, 1);
> -}

This function should be kept

> -
> -/*
> - * Initialize all reports
> - */
> -static void i2c_hid_init_reports(struct hid_device *hid)
> -{
> -       struct hid_report *report;
> -       struct i2c_client *client = hid->driver_data;
> -       struct i2c_hid *ihid = i2c_get_clientdata(client);
> -       u8 *inbuf = kzalloc(ihid->bufsize, GFP_KERNEL);
> -
> -       if (!inbuf) {
> -               dev_err(&client->dev, "can not retrieve initial reports\n");
> -               return;
> -       }
> -

Above should be kept

> -       list_for_each_entry(report,
> -               &hid->report_enum[HID_INPUT_REPORT].report_list, list)
> -               i2c_hid_init_report(report, inbuf, ihid->bufsize);
> -

these for lines should be removed (they are the one giving the errors
in the logs)

and please keep the rest of the code as is.


> -       list_for_each_entry(report,
> -               &hid->report_enum[HID_FEATURE_REPORT].report_list, list)
> -               i2c_hid_init_report(report, inbuf, ihid->bufsize);

Actually, this part is very important because we have no spontaneous
events emitted by features, so we don't know the value of the feature
until we probed it. So please keep this part as mentioned above.

Cheers,
Benjamin

> -
> -       kfree(inbuf);
> -}
> -
>  /*
>   * Traverse the supplied list of reports and find the longest
>   */
> @@ -683,9 +627,6 @@ static int i2c_hid_start(struct hid_device *hid)
>                         return ret;
>         }
>
> -       if (!(hid->quirks & HID_QUIRK_NO_INIT_REPORTS))
> -               i2c_hid_init_reports(hid);
> -
>         return 0;
>  }
>
> --
> 1.8.1.5
>
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