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SubjectRe: [PATCH v2 3/3] drm: Allow simpledrm to setup its emulated FB as firmware provided
Hi Javier,

Thank you for the patch.

On Mon, May 02, 2022 at 05:39:00PM +0200, Javier Martinez Canillas wrote:
> Indicate to fbdev subsystem that the registered framebuffer is provided by
> the system firmware, so that it can handle accordingly. For example, would
> unregister the FB devices if asked to remove the conflicting framebuffers.
>
> Add a new DRM_FB_FW field to drm_fbdev_generic_setup() options parameter.
> Drivers can use this to indicate the FB helper initialization that the FB
> registered is provided by the firmware, so it can be configured as such.
>
> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>
> (no changes since v1)
>
> drivers/gpu/drm/drm_fb_helper.c | 9 +++++++++
> drivers/gpu/drm/tiny/simpledrm.c | 2 +-
> include/drm/drm_fb_helper.h | 10 ++++++++++
> 3 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index fd0084ad77c3..775e47c5de1f 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -1891,6 +1891,10 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper,
> /* don't leak any physical addresses to userspace */
> info->flags |= FBINFO_HIDE_SMEM_START;
>
> + /* Indicate that the framebuffer is provided by the firmware */
> + if (fb_helper->firmware)
> + info->flags |= FBINFO_MISC_FIRMWARE;
> +
> /* Need to drop locks to avoid recursive deadlock in
> * register_framebuffer. This is ok because the only thing left to do is
> * register the fbdev emulation instance in kernel_fb_helper_list. */
> @@ -2512,6 +2516,8 @@ static const struct drm_client_funcs drm_fbdev_client_funcs = {
> *
> * * DRM_FB_BPP: bits per pixel for the device. If the field is not set,
> * @dev->mode_config.preferred_depth is used instead.
> + * * DRM_FB_FW: if the framebuffer for the device is provided by the
> + * system firmware.
> *
> * This function sets up generic fbdev emulation for drivers that supports
> * dumb buffers with a virtual address and that can be mmap'ed.
> @@ -2538,6 +2544,7 @@ void drm_fbdev_generic_setup(struct drm_device *dev, unsigned int options)
> {
> struct drm_fb_helper *fb_helper;
> unsigned int preferred_bpp = DRM_FB_GET_OPTION(DRM_FB_BPP, options);
> + bool firmware = DRM_FB_GET_OPTION(DRM_FB_FW, options);
> int ret;
>
> drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
> @@ -2570,6 +2577,8 @@ void drm_fbdev_generic_setup(struct drm_device *dev, unsigned int options)
> preferred_bpp = 32;
> fb_helper->preferred_bpp = preferred_bpp;
>
> + fb_helper->firmware = firmware;

I'd get rid of the local variable and write

fb_helper->firmware = DRM_FB_GET_OPTION(DRM_FB_FW, options);

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> +
> ret = drm_fbdev_client_hotplug(&fb_helper->client);
> if (ret)
> drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
> diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
> index f5b8e864a5cd..5dcc21ea6180 100644
> --- a/drivers/gpu/drm/tiny/simpledrm.c
> +++ b/drivers/gpu/drm/tiny/simpledrm.c
> @@ -901,7 +901,7 @@ static int simpledrm_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> - drm_fbdev_generic_setup(dev, 0);
> + drm_fbdev_generic_setup(dev, DRM_FB_SET_OPTION(DRM_FB_FW, 1));
>
> return 0;
> }
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 740f87560102..77a72d55308d 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -44,6 +44,7 @@ enum mode_set_atomic {
> };
>
> #define DRM_FB_BPP_MASK GENMASK(7, 0)
> +#define DRM_FB_FW_MASK GENMASK(8, 8)
>
> /* Using the GNU statement expression extension */
> #define DRM_FB_OPTION(option, value) \
> @@ -197,6 +198,15 @@ struct drm_fb_helper {
> * See also: @deferred_setup
> */
> int preferred_bpp;
> +
> + /**
> + * @firmware:
> + *
> + * Set if the driver indicates to the FB helper initialization that the
> + * framebuffer for the device being registered is provided by firmware,
> + * so that it can pass this on when registering the framebuffer device.
> + */
> + bool firmware;
> };
>
> static inline struct drm_fb_helper *

--
Regards,

Laurent Pinchart

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