On Tue, Sep 30, 2025 at 09:26:55PM +0000, Jonathan Cavitt wrote:
> Add a helper function that computes the product of hdisplay and
> vdisplay.
>
> Signed-off-by: Jonathan Cavitt <[email protected]>
> Cc: Matthew Auld <[email protected]>
> Cc: Himal Prasad Ghimiray <[email protected]>
> Cc: Matthew Brost <[email protected]>
> ---
> drivers/gpu/drm/drm_gem_vram_helper.c | 2 +-
> drivers/gpu/drm/drm_mipi_dbi.c | 2 +-
> include/drm/drm_modes.h | 5 +++++
> 3 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c
> b/drivers/gpu/drm/drm_gem_vram_helper.c
> index 90760d0ca071..4ac71c34f4c6 100644
> --- a/drivers/gpu/drm/drm_gem_vram_helper.c
> +++ b/drivers/gpu/drm/drm_gem_vram_helper.c
> @@ -967,7 +967,7 @@ drm_vram_helper_mode_valid_internal(struct drm_device
> *dev,
>
> max_fbpages = (vmm->vram_size / 2) >> PAGE_SHIFT;
>
> - fbsize = mode->hdisplay * mode->vdisplay * max_bpp;
This calculation is quite inaccurate since it doesn't
consider any stride alignment requirements. Maybe it works
for a few cases, but certainly not usable on most hardware.
> + fbsize = drm_mode_display_size(mode) * max_bpp;
> fbpages = DIV_ROUND_UP(fbsize, PAGE_SIZE);
>
> if (fbpages > max_fbpages)
> diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
> index e33c78fc8fbd..54212bf85160 100644
> --- a/drivers/gpu/drm/drm_mipi_dbi.c
> +++ b/drivers/gpu/drm/drm_mipi_dbi.c
> @@ -691,7 +691,7 @@ int mipi_dbi_dev_init(struct mipi_dbi_dev *dbidev,
> const struct drm_simple_display_pipe_funcs *funcs,
> const struct drm_display_mode *mode, unsigned int
> rotation)
> {
> - size_t bufsize = mode->vdisplay * mode->hdisplay * sizeof(u16);
> + size_t bufsize = drm_mode_display_size(mode) * sizeof(u16);
>
> dbidev->drm.mode_config.preferred_depth = 16;
>
> diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
> index b9bb92e4b029..775c94c55cda 100644
> --- a/include/drm/drm_modes.h
> +++ b/include/drm/drm_modes.h
> @@ -572,4 +572,9 @@ struct drm_display_mode *
> drm_mode_create_from_cmdline_mode(struct drm_device *dev,
> struct drm_cmdline_mode *cmd);
>
> +static inline u32 drm_mode_display_size(const struct drm_display_mode *mode)
"display size" isn't really a term that gives me any kind of idea
what this does, so the name is rather poor. drm_mode_num_active_pixels()
or something might make more sense. But I'm not sure there's much
point in this helper since that value is very rarely useful for
anything.
> +{
> + return mode->hdisplay * mode->vdisplay;
> +}
> +
> #endif /* __DRM_MODES_H__ */
> --
> 2.43.0
--
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