Messages in this thread Patch in this message | | | Date | Wed, 12 Apr 2023 12:39:46 +0200 | Subject | Re: [PATCH v3 1/9] drm/mediatek: dp: Cache EDID for eDP panel | From | Matthias Brugger <> |
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On 12/04/2023 10:06, AngeloGioacchino Del Regno wrote: > Il 12/04/23 09:08, Matthias Brugger ha scritto: >> >> >> On 04/04/2023 12:47, AngeloGioacchino Del Regno wrote: >>> Since eDP panels are not removable it is safe to cache the EDID: >>> this will avoid a relatively long read transaction at every PM >>> resume that is unnecessary only in the "special" case of eDP, >>> hence speeding it up a little, as from now on, as resume operation, >>> we will perform only link training. >>> >>> Signed-off-by: AngeloGioacchino Del Regno >>> <angelogioacchino.delregno@collabora.com> >>> --- >>> drivers/gpu/drm/mediatek/mtk_dp.c | 11 ++++++++++- >>> 1 file changed, 10 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c >>> b/drivers/gpu/drm/mediatek/mtk_dp.c >>> index 1f94fcc144d3..84f82cc68672 100644 >>> --- a/drivers/gpu/drm/mediatek/mtk_dp.c >>> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c >>> @@ -118,6 +118,7 @@ struct mtk_dp { >>> const struct mtk_dp_data *data; >>> struct mtk_dp_info info; >>> struct mtk_dp_train_info train_info; >>> + struct edid *edid; >>> struct platform_device *phy_dev; >>> struct phy *phy; >>> @@ -1993,7 +1994,11 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge >>> *bridge, >>> usleep_range(2000, 5000); >>> } >>> - new_edid = drm_get_edid(connector, &mtk_dp->aux.ddc); >>> + /* eDP panels aren't removable, so we can return a cached EDID. */ >>> + if (mtk_dp->edid && mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP)
Maybe better like this: if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP && mtk_dp->edid)
To in sync with the if statement below. Anyway we are only concerned if it's an eDP so check that first (and hope the compiler will do so as well ;)
With that: Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
>>> + new_edid = drm_edid_duplicate(mtk_dp->edid); >>> + else >>> + new_edid = drm_get_edid(connector, &mtk_dp->aux.ddc); >> >> Maybe it would make sense to add a macro for the check of mtk_dp->bridge.type >> == DRM_MODE_CONNECTOR_eDP >> it would make the code more readable. >> > > I had the same idea... but then avoided that because in most (if not all?) of the > DRM drivers (at least, the one I've read) this check is always open coded, so I > wrote it like that for consistency and nothing else. > > I have no strong opinions on that though! >
I think the only reasonable solution would be a macro like: DRM_CONNECTOR_MODE_IS(mtk_dp->bridge.type, eDP) which in the end is longer then open-code it, so probably just leave it as it is.
>>> /* >>> * Parse capability here to let atomic_get_input_bus_fmts and >>> @@ -2022,6 +2027,10 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge >>> *bridge, >>> drm_atomic_bridge_chain_post_disable(bridge, connector->state->state); >>> } >>> + /* If this is an eDP panel and the read EDID is good, cache it for later */ >>> + if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP && !mtk_dp->edid && >>> new_edid) >>> + mtk_dp->edid = drm_edid_duplicate(new_edid); >>> + >> >> How about putting this in an else if branch of mtk_dp_parse_capabilities. At >> least we could get rid of the check regarding if new_edid != NULL. >> >> I was thinking on how to put both if statements in one block, but I think the >> problem is, that we would leak memory if the capability parsing failes due to >> the call to drm_edid_duplicate(). Correct? >> > > Correct. The only other "good" place would be in the `if (new_edid)` conditional, > but that wouldn't be as readable as it is right now... > > Cheers, > Angelo >
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