[PATCH 01/43] drm/fbdev-generic: Do not set physical framebuffer address

[Thomas Zimmermann]

Hi

Am 18.03.24 um 03:35 schrieb Zack Rusin:
> On Tue, Mar 12, 2024 at 11:48 AM Thomas Zimmermann <tzimmermann at suse.de> wrote:
>> Framebuffer memory is allocated via vmalloc() from non-contiguous
>> physical pages. The physical framebuffer start address is therefore
>> meaningless. Do not set it.
>>
>> The value is not used within the kernel and only exported to userspace
>> on dedicated ARM configs. No functional change is expected.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>> Fixes: a5b44c4adb16 ("drm/fbdev-generic: Always use shadow buffering")
>> Cc: Thomas Zimmermann <tzimmermann at suse.de>
>> Cc: Javier Martinez Canillas <javierm at redhat.com>
>> Cc: Zack Rusin <zackr at vmware.com>
>> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> Cc: Maxime Ripard <mripard at kernel.org>
>> Cc: <stable at vger.kernel.org> # v6.4+
>> ---
>>   drivers/gpu/drm/drm_fbdev_generic.c | 1 -
>>   1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
>> index d647d89764cb9..b4659cd6285ab 100644
>> --- a/drivers/gpu/drm/drm_fbdev_generic.c
>> +++ b/drivers/gpu/drm/drm_fbdev_generic.c
>> @@ -113,7 +113,6 @@ static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper,
>>          /* screen */
>>          info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
>>          info->screen_buffer = screen_buffer;
>> -       info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
>>          info->fix.smem_len = screen_size;
>>
>>          /* deferred I/O */
>> --
>> 2.44.0
>>
> Good idea. I think given that drm_leak_fbdev_smem is off by default we
> could remove the setting of smem_start by all of the in-tree drm
> drivers (they all have open source userspace that won't mess around
> with fbdev fb) - it will be reset to 0 anyway. Actually, I wonder if
> we still need drm_leak_fbdev_smem at all...

All I know is that there's an embedded userspace driver that requires 
that setting. I don't even know which hardware.

Best regards
Thomas

>
> Reviewed-by: Zack Rusin <zack.rusin at broadcom.com>
>
> z

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)