linux-kernel - [RESEND][PATCH] drm/bridge: analogix-anx6345: Fix drm_dp

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Message-Id: <20200218154745.BCB6D68BFE@verein.lst.de>
Date:   Tue, 18 Feb 2020 16:47:45 +0100 (CET)
From:   Torsten Duwe <duwe@....de>
To:     Maxime Ripard <maxime@...no.tech>, Daniel Vetter <daniel@...ll.ch>
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [RESEND][PATCH] drm/bridge: analogix-anx6345: Fix drm_dp_link helper removal

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: e1cff82c1097bda2478 ("fix anx6345 compilation for v5.5")
Signed-off-by: Torsten Duwe <duwe@...e.de>
---
https://patchwork.freedesktop.org/patch/343004/
https://lists.freedesktop.org/archives/dri-devel/2020-January/253535.html

--- a/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
@@ -210,10 +210,9 @@ 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]);
 	err = regmap_write(anx6345->map[I2C_IDX_DPTX],
-			   SP_DP_MAIN_LINK_BW_SET_REG, dpcd[0]);
+			   SP_DP_MAIN_LINK_BW_SET_REG,
+			   anx6345->dpcd[DP_MAX_LINK_RATE]);
 	if (err)
 		return err;