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drm/bridge: analogix-anx6345: fix set of link bandwidth 

Current code tries to store the link rate (in bps, which is a big
number) in a u8, which surely overflow. Then it's converted back to
bandwidth code (which is thus 0) and written to the chip.

The code sometimes works because the chip will automatically fallback to
the lowest possible DP link rate (1.62Gbps) when get the invalid value.
However, on the eDP panel of Olimex TERES-I, which wants 2.7Gbps link,
it failed.

As we had already read the link bandwidth as bandwidth code in earlier
code (to check whether it is supported), use it when setting bandwidth,
instead of converting it to link rate and then converting back.

Fixes: e1cff82c10 ("drm/bridge: fix anx6345 compilation for v5.5")
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Torsten Duwe <duwe@suse.de>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Torsten Duwe <duwe@lst.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Icenowy Zheng <icenowy@aosc.io>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20200221165127.813325-1-icenowy@aosc.io
This commit is contained in:
Icenowy Zheng 2020-02-22 00:51:27 +08:00 committed by Thomas Zimmermann
parent 8c8c06207b
commit 2be30d34a3
1 changed files with 1 additions and 2 deletions
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3
drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
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@ -210,8 +210,7 @@ static int anx6345_dp_link_training(struct anx6345 *anx6345)
if (err)
return err;
dpcd[0] = drm_dp_max_link_rate(anx6345->dpcd);
dpcd[0] = drm_dp_link_rate_to_bw_code(dpcd[0]);
dpcd[0] = dp_bw;
err = regmap_write(anx6345->map[I2C_IDX_DPTX],
SP_DP_MAIN_LINK_BW_SET_REG, dpcd[0]);
if (err)