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[07/18] drm/bridge: cdns-dsi: Fail if HS rate changed when validating PHY config

Message ID 20250320-cdns-dsi-impro-v1-7-725277c5f43b@ideasonboard.com (mailing list archive)
State New
Headers show
Series drm/bridge: cdns-dsi: Make it work a bit better | expand

Commit Message

Tomi Valkeinen March 20, 2025, 4 p.m. UTC
The phy_validate() can change the HS clock rate we passed to it in the
PHY config, depending on what the HW can actually do. The driver just
ignores this at the moment, but if the actual HS clock rate is different
than the requested one, the pipeline will fail as all the DSI timing
calculations will be incorrect.

There are ways to improve DSI operation for various clock rates, but for
now, just add a check to see if the rate changed, and return an error if
that happens.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
index 53322407c1b0..9238acf69823 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
@@ -580,6 +580,7 @@  static int cdns_dsi_check_conf(struct cdns_dsi *dsi,
 	unsigned long dsi_hss_hsa_hse_hbp;
 	unsigned int nlanes = output->dev->lanes;
 	int mode_clock = (mode_valid_check ? mode->clock : mode->crtc_clock);
+	unsigned long req_hs_clk_rate;
 	int ret;
 
 	ret = cdns_dsi_mode2cfg(dsi, mode, dsi_cfg, mode_valid_check);
@@ -596,10 +597,20 @@  static int cdns_dsi_check_conf(struct cdns_dsi *dsi,
 	if (ret)
 		return ret;
 
+	req_hs_clk_rate = output->phy_opts.mipi_dphy.hs_clk_rate;
 	ret = phy_validate(dsi->dphy, PHY_MODE_MIPI_DPHY, 0, &output->phy_opts);
 	if (ret)
 		return ret;
 
+	if (req_hs_clk_rate != output->phy_opts.mipi_dphy.hs_clk_rate) {
+		dev_err(&dsi->dphy->dev,
+			"validation changed hs_clk_rate from %lu to %lu, diff %lu\n",
+			req_hs_clk_rate, output->phy_opts.mipi_dphy.hs_clk_rate,
+			output->phy_opts.mipi_dphy.hs_clk_rate -
+				req_hs_clk_rate);
+		return -EINVAL;
+	}
+
 	dsi_hss_hsa_hse_hbp = dsi_cfg->hbp + DSI_HBP_FRAME_OVERHEAD;
 	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
 		dsi_hss_hsa_hse_hbp += dsi_cfg->hsa + DSI_HSA_FRAME_OVERHEAD;