linux-kernel - Re: [PATCH] Fix failure of simpledrm probe when trying to grab FB from the EFI-based Framebuffer

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Date:   Sat, 11 Nov 2023 19:31:11 +1100
From:   Andrew Worsley <amworsley@...il.com>
To:     Thomas Zimmermann <tzimmermann@...e.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVER FOR FIRMWARE FRAMEBUFFERS" 
        <dri-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Fix failure of simpledrm probe when trying to grab FB
 from the EFI-based Framebuffer

It's inline - part of the email - not an attachment?

I can see it in the copy that went to me...

Andrew

On Sat, 11 Nov 2023 at 15:30, Andrew Worsley <amworsley@...il.com> wrote:
>
>    The simpledrm.c does not call aperture_remove_conflicting_devices() in it's probe
>    function as the drivers/video/aperture.c documentation says it should. Consequently
>    it's request for the FB memory fails.
>
> ...
> [    3.085302] simple-framebuffer bd58dc000.framebuffer: [drm] *ERROR* could not acquire memory range [??? 0xffff6e1d8629d580-0x2a5000001a7 flags 0x0]: -16
> [    3.086433] simple-framebuffer: probe of bd58dc000.framebuffer failed with error -16
> ...
>
>    In my case no driver provided /dev/dri/card0 device is available on boot up and X
>    fails to start as per this from X start up log.
>
> ...
> [     5.616] (WW) Falling back to old probe method for modesetting
> [     5.616] (EE) open /dev/dri/card0: No such file or directory
> ...
>
>    Fault confirmed and fixed on Asahi 6.5.0 kernel with both CONFIG_FB_EFI and
>    CONFIG_DRM_SIMPLEDRM config options set.
>
> Signed-off-by: Andrew Worsley <amworsley@...il.com>
> ---
>  drivers/gpu/drm/tiny/simpledrm.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
> index 5fefc895bca2..e55a536b04cf 100644
> --- a/drivers/gpu/drm/tiny/simpledrm.c
> +++ b/drivers/gpu/drm/tiny/simpledrm.c
> @@ -8,6 +8,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/pm_domain.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/aperture.h>
>
>  #include <drm/drm_aperture.h>
>  #include <drm/drm_atomic.h>
> @@ -828,6 +829,13 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
>         if (mem) {
>                 void *screen_base;
>
> +               ret = aperture_remove_conflicting_devices(mem->start, resource_size(mem),
> +                       DRIVER_NAME);
> +               if (ret) {
> +                       drm_err(dev, "aperture_remove_conflicting_devices: failed:%d\n",
> +                           __func__, ret);
> +                       return ERR_PTR(ret);
> +               }
>                 ret = devm_aperture_acquire_from_firmware(dev, mem->start, resource_size(mem));
>                 if (ret) {
>                         drm_err(dev, "could not acquire memory range %pr: %d\n", mem, ret);
> @@ -848,6 +856,13 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
>                 if (!res)
>                         return ERR_PTR(-EINVAL);
>
> +               ret = aperture_remove_conflicting_devices(res->start, resource_size(res),
> +                       DRIVER_NAME);
> +               if (ret) {
> +                       drm_err(dev, "aperture_remove_conflicting_devices: failed:%d\n",
> +                           __func__, ret);
> +                       return ERR_PTR(ret);
> +               }
>                 ret = devm_aperture_acquire_from_firmware(dev, res->start, resource_size(res));
>                 if (ret) {
>                         drm_err(dev, "could not acquire memory range %pr: %d\n", res, ret);
> --
> 2.42.0
>