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SubjectRe: [PATCH v1] drm/modes: Skip invalid cmdline mode
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10.07.2019 13:00, Ville Syrjälä пишет:
> On Tue, Jul 09, 2019 at 05:51:51PM +0300, Dmitry Osipenko wrote:
>> The named mode could be invalid and then cmdline parser misses to validate
>> mode's dimensions, happily adding 0x0 mode as a valid mode. One case where
>> this happens is NVIDIA Tegra devices that are using downstream bootloader
>> which adds "video=tegrafb" to the kernel's cmdline and thus upstream Tegra
>> DRM driver fails to probe because of the invalid mode.
>>
>> Fixes: 3aeeb13d8996 ("drm/modes: Support modes names on the command line")
>
> Is that actually true? This problem has been in the code since forever AFAICS.

Yes, it's a problem now because named mode is marked as specified and
everything that do not match to a non-named mode is treated as named.

>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>> drivers/gpu/drm/drm_client_modeset.c | 3 ++-
>> drivers/gpu/drm/drm_modes.c | 6 ++++++
>> 2 files changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
>> index e95fceac8f8b..56d36779d213 100644
>> --- a/drivers/gpu/drm/drm_client_modeset.c
>> +++ b/drivers/gpu/drm/drm_client_modeset.c
>> @@ -180,7 +180,8 @@ drm_connector_pick_cmdline_mode(struct drm_connector *connector)
>>
>> create_mode:
>> mode = drm_mode_create_from_cmdline_mode(connector->dev, cmdline_mode);
>> - list_add(&mode->head, &connector->modes);
>> + if (mode)
>> + list_add(&mode->head, &connector->modes);
>
> That's the same as what I did here
> https://patchwork.freedesktop.org/patch/309223/?series=61781&rev=1
>
> But I'd have to rebase that so let's just go with your patch.
>
>>
>> return mode;
>> }
>> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
>> index 910561d4f071..74a5739df506 100644
>> --- a/drivers/gpu/drm/drm_modes.c
>> +++ b/drivers/gpu/drm/drm_modes.c
>> @@ -158,6 +158,9 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay,
>> int interlace;
>> u64 tmp;
>>
>> + if (!hdisplay || !vdisplay)
>> + return NULL;
>> +
>> /* allocate the drm_display_mode structure. If failure, we will
>> * return directly
>> */
>> @@ -392,6 +395,9 @@ drm_gtf_mode_complex(struct drm_device *dev, int hdisplay, int vdisplay,
>> int hsync, hfront_porch, vodd_front_porch_lines;
>> unsigned int tmp1, tmp2;
>>
>> + if (!hdisplay || !vdisplay)
>> + return NULL;
>> +
>
> These lgtm
>
> Patch is
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Thanks!

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