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drm/bridge: adv7533: Fix adv7533_mode_valid for adv7533 and adv7535

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[ 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@kernel.org>
Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230319125524.58803-1-aford173@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Adam Ford 2023-03-19 07:55:24 -05:00 committed by Greg Kroah-Hartman
parent 1f141fe515
commit 052d22acd7
1 changed files with 10 additions and 13 deletions
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23
drivers/gpu/drm/bridge/adv7511/adv7533.c
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@ -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;
/* Check max clock for either 7533 or 7535 */
if (mode->clock > (adv->type == ADV7533 ? 80000 : 148500))
return MODE_CLOCK_HIGH;
/*
* 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 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;
}