[RESEND][PATCH] drm/bridge: analogix-anx78xx: Fix drm_dp_link helper removal

From: Torsten Duwe
Date: Tue Feb 18 2020 - 10:57:49 EST


drm_dp_link_rate_to_bw_code and ...bw_code_to_link_rate simply divide by
and multiply with 27000, respectively. Avoid an overflow in the u8 dpcd[0]
and the multiply+divide alltogether.

fixes: ff1e8fb68ea06027 ("analogix-anx78xx: Avoid drm_dp_link helpers")
Signed-off-by: Torsten Duwe <duwe@xxxxxxx>
Reviewed-by: Thierry Reding <treding@xxxxxxxxxx>
---
https://patchwork.freedesktop.org/patch/343003/ (dropped the review mark)
https://lists.freedesktop.org/archives/dri-devel/2020-January/253535.html

---
diff --git a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
index 41867be03751..864423f59d66 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
@@ -722,10 +722,9 @@ static int anx78xx_dp_link_training(struct anx78xx *anx78xx)
if (err)
return err;

- dpcd[0] = drm_dp_max_link_rate(anx78xx->dpcd);
- dpcd[0] = drm_dp_link_rate_to_bw_code(dpcd[0]);
err = regmap_write(anx78xx->map[I2C_IDX_TX_P0],
- SP_DP_MAIN_LINK_BW_SET_REG, dpcd[0]);
+ SP_DP_MAIN_LINK_BW_SET_REG,
+ anx78xx->dpcd[DP_MAX_LINK_RATE]);
if (err)
return err;