From: Adam Ford <aford173@xxxxxxxxx>
[ Upstream commit ee0285e13455fdbce5de315bdbe91b5f198a2a06 ]
When dynamically switching lanes was removed, the intent of the code
was to check to make sure that higher speed items used 4 lanes, but
it had the unintended consequence of removing the slower speeds for
4-lane users.
This attempts to remedy this by doing a check to see that the
max frequency doesn't exceed the chip limit, and a second
check to make sure that the max bit-rate doesn't exceed the
number of lanes * max bit rate / lane.
Fixes: 9a0cdcd6649b ("drm/bridge: adv7533: remove dynamic lane switching from adv7533 bridge")
Reviewed-by: Robert Foss <rfoss@xxxxxxxxxx>
Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
Signed-off-by: Robert Foss <rfoss@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230319125524.58803-1-aford173@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/bridge/adv7511/adv7533.c | 25 +++++++++++-------------
1 file changed, 11 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
index fdfeadcefe805..7e3e56441aedc 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
@@ -103,22 +103,19 @@ void adv7533_dsi_power_off(struct adv7511 *adv)
enum drm_mode_status adv7533_mode_valid(struct adv7511 *adv,
const struct drm_display_mode *mode)
{
- int lanes;
+ unsigned long max_lane_freq;
struct mipi_dsi_device *dsi = adv->dsi;
+ u8 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
- if (mode->clock > 80000)
- lanes = 4;
- else
- lanes = 3;
-
- /*
- * TODO: add support for dynamic switching of lanes
- * by using the bridge pre_enable() op . Till then filter
- * out the modes which shall need different number of lanes
- * than what was configured in the device tree.
- */
- if (lanes != dsi->lanes)
- return MODE_BAD;
+ /* Check max clock for either 7533 or 7535 */
+ if (mode->clock > (adv->type == ADV7533 ? 80000 : 148500))
+ return MODE_CLOCK_HIGH;
+
+ /* Check max clock for each lane */
+ max_lane_freq = (adv->type == ADV7533 ? 800000 : 891000);
+
+ if (mode->clock * bpp > max_lane_freq * adv->num_dsi_lanes)
+ return MODE_CLOCK_HIGH;
return MODE_OK;
}
--
2.39.2
