Re: [PATCH 04/11] HID: logitech-dj: remove hidinput_input_event

From: David Herrmann
Date: Mon Feb 03 2014 - 12:07:43 EST


Hi

On Mon, Feb 3, 2014 at 5:21 PM, Benjamin Tissoires
<benjamin.tissoires@xxxxxxxxx> wrote:
> On Mon, Feb 3, 2014 at 11:06 AM, David Herrmann <dh.herrmann@xxxxxxxxx> wrote:
>> Hi
>>
>> On Sun, Feb 2, 2014 at 5:50 AM, Benjamin Tissoires
>> <benjamin.tissoires@xxxxxxxxxx> wrote:
>>> hid-logitech-dj uses its own ->hidinput_input_event() instead of
>>> the generic binding in hid-input.
>>> Moving the handling of LEDs towards logi_dj_output_hidraw_report()
>>> allows two things:
>>> - remove hidinput_input_event in struct hid_device
>>> - hidraw user space programs can also set the LEDs
>>>
>>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
>>> ---
>>> drivers/hid/hid-logitech-dj.c | 99 +++++++++++++++----------------------------
>>> 1 file changed, 35 insertions(+), 64 deletions(-)
>>>
>>> diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
>>> index f45279c..61d2bbf 100644
>>> --- a/drivers/hid/hid-logitech-dj.c
>>> +++ b/drivers/hid/hid-logitech-dj.c
>>> @@ -44,14 +44,6 @@ static const char kbd_descriptor[] = {
>>> 0x19, 0xE0, /* USAGE_MINIMUM (Left Control) */
>>> 0x29, 0xE7, /* USAGE_MAXIMUM (Right GUI) */
>>> 0x81, 0x02, /* INPUT (Data,Var,Abs) */
>>> - 0x95, 0x05, /* REPORT COUNT (5) */
>>> - 0x05, 0x08, /* USAGE PAGE (LED page) */
>>> - 0x19, 0x01, /* USAGE MINIMUM (1) */
>>> - 0x29, 0x05, /* USAGE MAXIMUM (5) */
>>> - 0x91, 0x02, /* OUTPUT (Data, Variable, Absolute) */
>>> - 0x95, 0x01, /* REPORT COUNT (1) */
>>> - 0x75, 0x03, /* REPORT SIZE (3) */
>>> - 0x91, 0x01, /* OUTPUT (Constant) */
>>> 0x95, 0x06, /* REPORT_COUNT (6) */
>>> 0x75, 0x08, /* REPORT_SIZE (8) */
>>> 0x15, 0x00, /* LOGICAL_MINIMUM (0) */
>>> @@ -60,6 +52,18 @@ static const char kbd_descriptor[] = {
>>> 0x19, 0x00, /* USAGE_MINIMUM (no event) */
>>> 0x2A, 0xFF, 0x00, /* USAGE_MAXIMUM (reserved) */
>>> 0x81, 0x00, /* INPUT (Data,Ary,Abs) */
>>> + 0x85, 0x0e, /* REPORT_ID (14) */
>>> + 0x05, 0x08, /* USAGE PAGE (LED page) */
>>> + 0x95, 0x05, /* REPORT COUNT (5) */
>>> + 0x75, 0x01, /* REPORT SIZE (1) */
>>> + 0x15, 0x00, /* LOGICAL_MINIMUM (0) */
>>> + 0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
>>> + 0x19, 0x01, /* USAGE MINIMUM (1) */
>>> + 0x29, 0x05, /* USAGE MAXIMUM (5) */
>>> + 0x91, 0x02, /* OUTPUT (Data, Variable, Absolute) */
>>> + 0x95, 0x01, /* REPORT COUNT (1) */
>>> + 0x75, 0x03, /* REPORT SIZE (3) */
>>> + 0x91, 0x01, /* OUTPUT (Constant) */
>>> 0xC0
>>> };
>>>
>>> @@ -544,10 +548,30 @@ static int logi_dj_output_hidraw_report(struct hid_device *hid, u8 * buf,
>>> size_t count,
>>> unsigned char report_type)
>>> {
>>> - /* Called by hid raw to send data */
>>> - dbg_hid("%s\n", __func__);
>>> + struct dj_device *djdev = hid->driver_data;
>>> + struct dj_receiver_dev *djrcv_dev = djdev->dj_receiver_dev;
>>> + u8 *out_buf;
>>> + int ret;
>>>
>>> - return 0;
>>> + if (buf[0] != REPORT_TYPE_LEDS)
>>> + return -EINVAL;
>>> +
>>> + out_buf = kzalloc(DJREPORT_SHORT_LENGTH, GFP_ATOMIC);
>>> + if (!out_buf)
>>> + return -ENOMEM;
>>> +
>>> + if (count < DJREPORT_SHORT_LENGTH - 2)
>>> + count = DJREPORT_SHORT_LENGTH - 2;
>>> +
>>> + out_buf[0] = REPORT_ID_DJ_SHORT;
>>> + out_buf[1] = djdev->device_index;
>>> + memcpy(out_buf + 2, buf, count);
>>> +
>>> + ret = djrcv_dev->hdev->hid_output_raw_report(djrcv_dev->hdev, out_buf,
>>> + DJREPORT_SHORT_LENGTH, report_type);
>>
>> Strictly speaking the code below uses HID_REQ_SET_REPORT and you
>> replace it with hid_output_raw_report() here (which at least for BTHID
>> is not equivalent). Anyhow, HID-core uses hid_output_raw_report(),
>> too, so this should be fine.
>
> Yes, you are right. This fires back on me yesterday when I tried to
> remove the hid_output_raw_report() calls.
> It occurs it works because usbhid_out_raw_report() uses set_report
> when there is no urbout, which is the case with logitech receivers.
> So I guess an ideal solution would be to implement a hid_hw_request call.
>
> However, the only concern I have with hid_hw_request is that it does
> not allow hidraw to play with the LEDs given that hidraw does not have
> an ioctl for SET_REPORT (or GET_REPORT). I already seen this issue
> regarding i2c_hid at some point, but it was "solved" in i2c_hid by
> using the same ugly trick that we have in USB-hid.

Hah! That's why it worked all the years, USB-HID checks for !urbout..
and yeah, that's what I just criticized in your i2c-hid patch.. Ok,
I'm fine if we make output_report() fall back to SET_REPORT if not
output-channel is supported. But we it gets ugly if we rely on that
from the upper stack... hmm, don't know how to make that work but
adding a hid quirk to use SET_REPORT for hidinput_input_report().

Thanks
David
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