On Fri, Mar 25, 2022 at 02:25:24PM +0200, Jani Nikula wrote:
> Use struct member access instead of direct offsets to avoid lots of
> casts all over the place.
>
> Use BUILD_BUG_ON() for sanity check.
>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_edid.c | 26 +++++++++++++++-----------
> 1 file changed, 15 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 1b552fe54f38..48707eef1dc2 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2331,10 +2331,14 @@ struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
> }
> EXPORT_SYMBOL(drm_mode_find_dmt);
>
> -static bool is_display_descriptor(const u8 d[18], u8 tag)
> +static bool is_display_descriptor(const struct detailed_timing *timing, u8 type)
> {
> - return d[0] == 0x00 && d[1] == 0x00 &&
> - d[2] == 0x00 && d[3] == tag;
> + BUILD_BUG_ON(offsetof(typeof(*timing), pixel_clock) != 0);
> + BUILD_BUG_ON(offsetof(typeof(*timing), data.other_data.pad1) != 2);
> + BUILD_BUG_ON(offsetof(typeof(*timing), data.other_data.type) != 3);
> +
> + return timing->pixel_clock == 0 && timing->data.other_data.pad1 == 0 &&
This would probably be less confusing if we moved pixel_clock into
pixel_data and just had matching padding bytes/etc. in other_data.
The names of all structs are also rather weird. We should probably
change them to match the spec terminology a bit more closely:
18 byte descriptor,detailed timing descriptor,display descriptor.
But that's a separate topic.
> + timing->data.other_data.type == type;
> }
>
> static bool is_detailed_timing_descriptor(const u8 d[18])
> @@ -2405,7 +2409,7 @@ is_rb(struct detailed_timing *t, void *data)
> {
> u8 *r = (u8 *)t;
>
> - if (!is_display_descriptor(r, EDID_DETAIL_MONITOR_RANGE))
> + if (!is_display_descriptor(t, EDID_DETAIL_MONITOR_RANGE))
> return;
>
> if (r[15] & 0x10)
> @@ -2431,7 +2435,7 @@ find_gtf2(struct detailed_timing *t, void *data)
> {
> u8 *r = (u8 *)t;
>
> - if (!is_display_descriptor(r, EDID_DETAIL_MONITOR_RANGE))
> + if (!is_display_descriptor(t, EDID_DETAIL_MONITOR_RANGE))
> return;
>
> if (r[10] == 0x02)
> @@ -2987,7 +2991,7 @@ do_inferred_modes(struct detailed_timing *timing, void *c)
> struct detailed_non_pixel *data = &timing->data.other_data;
> struct detailed_data_monitor_range *range = &data->data.range;
>
> - if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_MONITOR_RANGE))
> + if (!is_display_descriptor(timing, EDID_DETAIL_MONITOR_RANGE))
> return;
>
> closure->modes += drm_dmt_modes_for_range(closure->connector,
> @@ -3067,7 +3071,7 @@ do_established_modes(struct detailed_timing *timing, void *c)
> {
> struct detailed_mode_closure *closure = c;
>
> - if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_EST_TIMINGS))
> + if (!is_display_descriptor(timing, EDID_DETAIL_EST_TIMINGS))
> return;
>
> closure->modes += drm_est3_modes(closure->connector, timing);
> @@ -3122,7 +3126,7 @@ do_standard_modes(struct detailed_timing *timing, void *c)
> struct edid *edid = closure->edid;
> int i;
>
> - if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_STD_MODES))
> + if (!is_display_descriptor(timing, EDID_DETAIL_STD_MODES))
> return;
>
> for (i = 0; i < 6; i++) {
> @@ -3231,7 +3235,7 @@ do_cvt_mode(struct detailed_timing *timing, void *c)
> {
> struct detailed_mode_closure *closure = c;
>
> - if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_CVT_3BYTE))
> + if (!is_display_descriptor(timing, EDID_DETAIL_CVT_3BYTE))
> return;
>
> closure->modes += drm_cvt_modes(closure->connector, timing);
> @@ -4491,7 +4495,7 @@ drm_parse_hdmi_vsdb_audio(struct drm_connector *connector, const u8 *db)
> static void
> monitor_name(struct detailed_timing *t, void *data)
> {
> - if (!is_display_descriptor((const u8 *)t, EDID_DETAIL_MONITOR_NAME))
> + if (!is_display_descriptor(t, EDID_DETAIL_MONITOR_NAME))
> return;
>
> *(u8 **)data = t->data.other_data.data.str.str;
> @@ -5226,7 +5230,7 @@ void get_monitor_range(struct detailed_timing *timing,
> const struct detailed_non_pixel *data = &timing->data.other_data;
> const struct detailed_data_monitor_range *range = &data->data.range;
>
> - if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_MONITOR_RANGE))
> + if (!is_display_descriptor(timing, EDID_DETAIL_MONITOR_RANGE))
> return;
>
> /*
> --
> 2.30.2
--
Ville Syrjälä
Intel
