linux-kernel - Re: [PATCH 03/14] HID: core: implement generic .request()

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Date:	Wed, 12 Feb 2014 11:25:54 +0100
From:	David Herrmann <dh.herrmann@...il.com>
To:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:	Benjamin Tissoires <benjamin.tissoires@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	"open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/14] HID: core: implement generic .request()

Hi

On Mon, Feb 10, 2014 at 6:58 PM, Benjamin Tissoires
<benjamin.tissoires@...hat.com> wrote:
> .request() can be emulated through .raw_request()
> we can implement this emulation in hid-core, and make .request
> not mandatory for transport layer drivers.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> ---
>  drivers/hid/hid-core.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/hid.h    |  5 ++++-
>  2 files changed, 48 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 18fe49b..f36778a 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1248,6 +1248,11 @@ void hid_output_report(struct hid_report *report, __u8 *data)
>  }
>  EXPORT_SYMBOL_GPL(hid_output_report);
>
> +static int hid_report_len(struct hid_report *report)
> +{
> +       return ((report->size - 1) >> 3) + 1 + (report->id > 0) + 7;

Just for clarity, this is equivalent to the following, right?

return DIV_ROUND_UP(report->size, 8) + !!(report->id > 0) + 7;

I always have to read that shifting code twice to get it.. Maybe add a
comment explaining the different entries here.

> +}
> +
>  /*
>   * Allocator for buffer that is going to be passed to hid_output_report()
>   */
> @@ -1258,7 +1263,7 @@ u8 *hid_alloc_report_buf(struct hid_report *report, gfp_t flags)
>          * of implement() working on 8 byte chunks
>          */
>
> -       int len = ((report->size - 1) >> 3) + 1 + (report->id > 0) + 7;
> +       int len = hid_report_len(report);
>
>         return kmalloc(len, flags);
>  }
> @@ -1314,6 +1319,44 @@ static struct hid_report *hid_get_report(struct hid_report_enum *report_enum,
>         return report;
>  }
>
> +/*
> + * Implement a generic .request() callback, using .raw_request()
> + * DO NOT USE in hid drivers directly, but through hid_hw_request instead.
> + */
> +void __hid_request(struct hid_device *hid, struct hid_report *report,
> +               int reqtype)
> +{
> +       char *buf;
> +       int ret;
> +       int len;
> +
> +       if (!hid->ll_driver->raw_request)
> +               return;
> +
> +       buf = hid_alloc_report_buf(report, GFP_KERNEL);
> +       if (!buf)
> +               return;
> +
> +       len = hid_report_len(report);
> +
> +       if (reqtype == HID_REQ_SET_REPORT)
> +               hid_output_report(report, buf);
> +
> +       ret = hid->ll_driver->raw_request(hid, report->id, buf, len,
> +                                         report->type, reqtype);
> +       if (ret < 0) {
> +               dbg_hid("unable to complete request: %d\n", ret);
> +               goto out;
> +       }
> +
> +       if (reqtype == HID_REQ_GET_REPORT)
> +               hid_input_report(hid, report->type, buf, ret, 0);
> +
> +out:
> +       kfree(buf);
> +}
> +EXPORT_SYMBOL_GPL(__hid_request);
> +

Looks good to me.

Reviewed-by: David Herrmann <dh.herrmann@...il.com>

Thanks
David

>  int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,
>                 int interrupt)
>  {
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index a837ede..09fbbd7 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -753,6 +753,7 @@ struct hid_field *hidinput_get_led_field(struct hid_device *hid);
>  unsigned int hidinput_count_leds(struct hid_device *hid);
>  __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code);
>  void hid_output_report(struct hid_report *report, __u8 *data);
> +void __hid_request(struct hid_device *hid, struct hid_report *rep, int reqtype);
>  u8 *hid_alloc_report_buf(struct hid_report *report, gfp_t flags);
>  struct hid_device *hid_allocate_device(void);
>  struct hid_report *hid_register_report(struct hid_device *device, unsigned type, unsigned id);
> @@ -965,7 +966,9 @@ static inline void hid_hw_request(struct hid_device *hdev,
>                                   struct hid_report *report, int reqtype)
>  {
>         if (hdev->ll_driver->request)
> -               hdev->ll_driver->request(hdev, report, reqtype);
> +               return hdev->ll_driver->request(hdev, report, reqtype);
> +
> +       __hid_request(hdev, report, reqtype);
>  }
>
>  /**
> --
> 1.8.3.1
>
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