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drm: bridge: ldb: Warn if LDB clock does not match requested link frequency

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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
This commit is contained in:
Alexander Stein
2022-12-08 07:55:38 +01:00
committed by Neil Armstrong
parent ae5a8dce3c
commit bd43a9844b
1 changed files with 19 additions and 4 deletions
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23
drivers/gpu/drm/bridge/fsl-ldb.c
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@@ -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 */