On Fri, Mar 25, 2022 at 02:25:25PM +0200, Jani Nikula wrote:
> Use struct detailed_timing member access instead of direct offsets to
> avoid casting.
>
> Use BUILD_BUG_ON() for sanity check.
>
> Cc: Ville Syrjälä
> Signed-off-by: Jani Nikula
>
> ---
>
> Note: Why can we use range.formula.cvt.flags directly in is_rb() while
> gtf2 functions check for range.flags == 0x02 first to ensure it's gtf2?
Looks to me like is_rb() is just borked.
Other weird stuff I just noticed is get_monitor_range() not doing
anything for flags!=0x1 cases. It also fails to handle the other
flags that were added to byte 4 in EDID 1.4.
> ---
> drivers/gpu/drm/drm_edid.c | 12 +++-
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 48707eef1dc2..5396fa78e864 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2405,15 +2405,17 @@ drm_for_each_detailed_block(u8 *raw_edid, detailed_cb
> *cb, void *closure)
> }
>
> static void
> -is_rb(struct detailed_timing *t, void *data)
> +is_rb(struct detailed_timing *timing, void *data)
> {
> - u8 *r = (u8 *)t;
> + bool *res = data;
>
> - if (!is_display_descriptor(t, EDID_DETAIL_MONITOR_RANGE))
> + if (!is_display_descriptor(timing, EDID_DETAIL_MONITOR_RANGE))
Calling this 'timing' when it's not is a bit confusing. I'd probably
rename it to something else for all the display descriptor cases.
> return;
>
> - if (r[15] & 0x10)
> - *(bool *)data = true;
> + BUILD_BUG_ON(offsetof(typeof(*timing),
> data.other_data.data.range.formula.cvt.flags) != 15);
> +
> + if (timing->data.other_data.data.range.formula.cvt.flags & 0x10)
> + *res = true;
> }
>
> /* EDID 1.4 defines this explicitly. For EDID 1.3, we guess, badly. */
> --
> 2.30.2
--
Ville Syrjälä
Intel
