Re: [PATCH] drm/tegra: add tiling FB modifiers

[Alexandre Courbot]

On 11/08/2016 06:07 PM, Erik Faye-Lund wrote:
> On Tue, Nov 8, 2016 at 8:50 AM, Alexandre Courbot <acourbot@xxxxxxxxxx> wrote:
>> Add FB modifiers to allow user-space to specify that a surface is in one
>> of the two tiling formats supported by Tegra chips, and add support in
>> the tegradrm driver to handle them properly. This is necessary for the
>> display controller to directly display buffers generated by the GPU.
>>
>> This feature is intended to replace the dedicated IOCTL enabled
>> by TEGRA_STAGING and to provide a non-staging alternative to that
>> solution.
>>
>> Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
>> ---
>>  drivers/gpu/drm/tegra/drm.c   |  2 ++
>>  drivers/gpu/drm/tegra/fb.c    | 23 +++++++++++++++++++---
>>  include/uapi/drm/drm_fourcc.h | 45 +++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 67 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
>> index a9630c2d6cb3..36b4b30a5164 100644
>> --- a/drivers/gpu/drm/tegra/drm.c
>> +++ b/drivers/gpu/drm/tegra/drm.c
>> @@ -161,6 +161,8 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
>>         drm->mode_config.max_width = 4096;
>>         drm->mode_config.max_height = 4096;
>>
>> +       drm->mode_config.allow_fb_modifiers = true;
>> +
>>         drm->mode_config.funcs = &tegra_drm_mode_funcs;
>>
>>         err = tegra_drm_fb_prepare(drm);
>> diff --git a/drivers/gpu/drm/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c
>> index e6d71fa4028e..2fded58b2ca5 100644
>> --- a/drivers/gpu/drm/tegra/fb.c
>> +++ b/drivers/gpu/drm/tegra/fb.c
>> @@ -52,9 +52,26 @@ int tegra_fb_get_tiling(struct drm_framebuffer *framebuffer,
>>                         struct tegra_bo_tiling *tiling)
>>  {
>>         struct tegra_fb *fb = to_tegra_fb(framebuffer);
>> -
>> -       /* TODO: handle YUV formats? */
>> -       *tiling = fb->planes[0]->tiling;
>> +       uint64_t modifier = fb->base.modifier[0];
>> +
>> +       switch (fourcc_mod_tegra_mod(modifier)) {
>> +       case NV_FORMAT_MOD_TEGRA_TILED:
>> +               tiling->mode = TEGRA_BO_TILING_MODE_TILED;
>> +               tiling->value = 0;
>> +               break;
>> +
>> +       case NV_FORMAT_MOD_TEGRA_16BX2_BLOCK(0):
>> +               tiling->mode = TEGRA_BO_TILING_MODE_BLOCK;
>> +               tiling->value = fourcc_mod_tegra_param(modifier);
>> +               if (tiling->value > 5)
>> +                       return -EINVAL;
> 
> Shouldn't this contain some hardware-check for the support? AFAIK, not
> all Tegras support all block-heights (if even this mode at all?)...

tegra_dc_setup_window does that check later (check the test on
dc->soc->supports_block_linear). At the moment no error message is
displayed though (and it seems like we are writing a stale value in
DC_WIN_BUFFER_ADDR_MODE if the SoC doesn't support block linear and the
tiling mode is TEGRA_BO_TILING_MODE_BLOCK?)