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authorAlexander Stein <alexander.stein@ew.tq-group.com>2022-12-08 09:55:38 +0300
committerNeil Armstrong <neil.armstrong@linaro.org>2023-01-19 10:50:50 +0300
commitbd43a9844bc6f78e00fdc91db47f6969d10c5ac5 (patch)
tree5c5d2c51de61a30e484536711cb5b7948793d5c6
parentae5a8dce3c86c1ea8e17910c3836b92a406f9ad8 (diff)
downloadlinux-bd43a9844bc6f78e00fdc91db47f6969d10c5ac5.tar.xz
drm: bridge: ldb: Warn if LDB clock does not match requested link frequency
The LDB clock needs to be exactly 7-times the pixel clock used by the display. Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com> Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20221208065538.1753666-1-alexander.stein@ew.tq-group.com
-rw-r--r--drivers/gpu/drm/bridge/fsl-ldb.c23
1 files changed, 19 insertions, 4 deletions
diff --git a/drivers/gpu/drm/bridge/fsl-ldb.c b/drivers/gpu/drm/bridge/fsl-ldb.c
index f9e0f8d99268..9bcba8fc57e7 100644
--- a/drivers/gpu/drm/bridge/fsl-ldb.c
+++ b/drivers/gpu/drm/bridge/fsl-ldb.c
@@ -66,6 +66,14 @@ static inline struct fsl_ldb *to_fsl_ldb(struct drm_bridge *bridge)
return container_of(bridge, struct fsl_ldb, bridge);
}
+static unsigned long fsl_ldb_link_frequency(struct fsl_ldb *fsl_ldb, int clock)
+{
+ if (fsl_ldb->lvds_dual_link)
+ return clock * 3500;
+ else
+ return clock * 7000;
+}
+
static int fsl_ldb_attach(struct drm_bridge *bridge,
enum drm_bridge_attach_flags flags)
{
@@ -85,6 +93,8 @@ static void fsl_ldb_atomic_enable(struct drm_bridge *bridge,
const struct drm_display_mode *mode;
struct drm_connector *connector;
struct drm_crtc *crtc;
+ unsigned long configured_link_freq;
+ unsigned long requested_link_freq;
bool lvds_format_24bpp;
bool lvds_format_jeida;
u32 reg;
@@ -128,10 +138,15 @@ static void fsl_ldb_atomic_enable(struct drm_bridge *bridge,
crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
mode = &crtc_state->adjusted_mode;
- if (fsl_ldb->lvds_dual_link)
- clk_set_rate(fsl_ldb->clk, mode->clock * 3500);
- else
- clk_set_rate(fsl_ldb->clk, mode->clock * 7000);
+ requested_link_freq = fsl_ldb_link_frequency(fsl_ldb, mode->clock);
+ clk_set_rate(fsl_ldb->clk, requested_link_freq);
+
+ configured_link_freq = clk_get_rate(fsl_ldb->clk);
+ if (configured_link_freq != requested_link_freq)
+ dev_warn(fsl_ldb->dev, "Configured LDB clock (%lu Hz) does not match requested LVDS clock: %lu Hz",
+ configured_link_freq,
+ requested_link_freq);
+
clk_prepare_enable(fsl_ldb->clk);
/* Program LDB_CTRL */