[PATCH v6 2/4] drm/rockchip: dw_hdmi: relax mode_valid hook

[Sascha Hauer]

The driver checks if the pixel clock of the given mode matches an entry
in the mpll config table. At least for the Synopsys phy the frequencies
in the mpll table are meant as a frequency range up to which the entry
works, not as a frequency that must match the pixel clock. Return
MODE_OK when the pixelclock is smaller than one of the mpll frequencies
to allow for more display resolutions.
Limit this behaviour to the Synopsys phy at the moment and keep the
current behaviour of forcing exact pixelclock rates for the other phys
until it has been sorted out how and if the vendor specific phys work
with non standard clock rates.

Tested-by: Michael Riesch <michael.riesch at wolfvision.net>
Link: https://lore.kernel.org/r/20220926080435.259617-2-s.hauer@pengutronix.de
Tested-by: Nicolas Frattaroli <frattaroli.nicolas at gmail.com>
Tested-by: Dan Johansen <strit at manjaro.org>
Link: https://lore.kernel.org/r/20230118132213.2911418-2-s.hauer@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 26 +++++++++++++++------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
index 2f4b8f64cbad3..7d8bf292fedce 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
@@ -74,6 +74,7 @@ struct rockchip_hdmi {
 	struct regmap *regmap;
 	struct rockchip_encoder encoder;
 	const struct rockchip_hdmi_chip_data *chip_data;
+	const struct dw_hdmi_plat_data *plat_data;
 	struct clk *ref_clk;
 	struct clk *grf_clk;
 	struct dw_hdmi *hdmi;
@@ -241,23 +242,32 @@ static int rockchip_hdmi_parse_dt(struct rockchip_hdmi *hdmi)
 }
 
 static enum drm_mode_status
-dw_hdmi_rockchip_mode_valid(struct dw_hdmi *hdmi, void *data,
+dw_hdmi_rockchip_mode_valid(struct dw_hdmi *dw_hdmi, void *data,
 			    const struct drm_display_info *info,
 			    const struct drm_display_mode *mode)
 {
+	struct rockchip_hdmi *hdmi = data;
 	const struct dw_hdmi_mpll_config *mpll_cfg = rockchip_mpll_cfg;
 	int pclk = mode->clock * 1000;
-	bool valid = false;
+	bool exact_match = hdmi->plat_data->phy_force_vendor;
 	int i;
 
 	for (i = 0; mpll_cfg[i].mpixelclock != (~0UL); i++) {
-		if (pclk == mpll_cfg[i].mpixelclock) {
-			valid = true;
-			break;
-		}
+		/*
+		 * For vendor specific phys force an exact match of the pixelclock
+		 * to preserve the original behaviour of the driver.
+		 */
+		if (exact_match && pclk == mpll_cfg[i].mpixelclock)
+			return MODE_OK;
+		/*
+		 * The Synopsys phy can work with pixelclocks up to the value given
+		 * in the corresponding mpll_cfg entry.
+		 */
+		if (!exact_match && pclk <= mpll_cfg[i].mpixelclock)
+			return MODE_OK;
 	}
 
-	return (valid) ? MODE_OK : MODE_BAD;
+	return MODE_BAD;
 }
 
 static void dw_hdmi_rockchip_encoder_disable(struct drm_encoder *encoder)
@@ -546,8 +556,10 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 		return -ENOMEM;
 
 	hdmi->dev = &pdev->dev;
+	hdmi->plat_data = plat_data;
 	hdmi->chip_data = plat_data->phy_data;
 	plat_data->phy_data = hdmi;
+	plat_data->priv_data = hdmi;
 	encoder = &hdmi->encoder.encoder;
 
 	encoder->possible_crtcs = drm_of_find_possible_crtcs(drm, dev->of_node);
-- 
2.30.2