Den 05.04.2020 15.47, skrev Daniel Vetter:
> On Sun, Apr 5, 2020 at 12:18 PM Noralf Trønnes <noralf@xxxxxxxxxxx> wrote:
>>
>>
>>
>> Den 03.04.2020 15.57, skrev Daniel Vetter:
>>> Also init the fbdev emulation before we register the device, that way
>>> we can rely on the auto-cleanup and simplify the probe error code even
>>> more.
>>>
>>> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
>>> Cc: Dave Airlie <airlied@xxxxxxxxxx>
>>> Cc: Sean Paul <sean@xxxxxxxxxx>
>>> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
>>> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
>>> Cc: Emil Velikov <emil.l.velikov@xxxxxxxxx>
>>> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
>>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>>> ---
>>> drivers/gpu/drm/udl/udl_drv.c | 36 +++++++++++------------------------
>>> 1 file changed, 11 insertions(+), 25 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c
>>> index 1ce2d865c36d..4ba5149fdd57 100644
>>> --- a/drivers/gpu/drm/udl/udl_drv.c
>>> +++ b/drivers/gpu/drm/udl/udl_drv.c
>>> @@ -57,27 +57,20 @@ static struct udl_device *udl_driver_create(struct usb_interface *interface)
>>> struct udl_device *udl;
>>> int r;
>>>
>>> - udl = kzalloc(sizeof(*udl), GFP_KERNEL);
>>> - if (!udl)
>>> - return ERR_PTR(-ENOMEM);
>>> -
>>> - r = drm_dev_init(&udl->drm, &driver, &interface->dev);
>>> - if (r) {
>>> - kfree(udl);
>>> - return ERR_PTR(r);
>>> - }
>>> + udl = devm_drm_dev_alloc(&interface->dev, &driver,
>>> + struct udl_device, drm);
>>> + if (IS_ERR(udl))
>>> + return udl;
>>>
>>> udl->udev = udev;
>>> udl->drm.dev_private = udl;
>>> - drmm_add_final_kfree(&udl->drm, udl);
>>>
>>> r = udl_init(udl);
>>> - if (r) {
>>> - drm_dev_put(&udl->drm);
>>> + if (r)
>>> return ERR_PTR(r);
>>> - }
>>>
>>> usb_set_intfdata(interface, udl);
>>> +
>>> return udl;
>>> }
>>>
>>> @@ -91,23 +84,17 @@ static int udl_usb_probe(struct usb_interface *interface,
>>> if (IS_ERR(udl))
>>> return PTR_ERR(udl);
>>>
>>> + r = drm_fbdev_generic_setup(&udl->drm, 0);
>>
>> It doesn't feel right to have a client open the device before the DRM
>> device itself is registered. I would prefer to keep it where it is but
>> ignore any errors. A failing client shouldn't prevent the driver from
>> probing. drm_fbdev_generic_setup() do print errors if it fails. So yeah,
>> in hindsight I should have made drm_fbdev_generic_setup() return void.
>
> Hm, we have all kinds of usage right now, some check for errors, some
> dont, some do this before drm_dev_register, some after. If your
> recommendation is to not check for errors then I'm happy to implement
> that, but we're a bit inconsistent. Maybe we should do a patch that at
> least always returns 0 no matter what, plus document that the return
> value shouldn't be checked?
Yeah, always returning zero and documenting it would be a good start.
I counted 41 drivers using generic fbdev now, didn't know it was that
much used. Only 11 drivers are hand rolling their own:
armada
gma500
amd
omapdrm
nouveau
i915
msm
tegra
exynos
radeon
rockchip
Noralf.
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