linux-kernel - Re: [PATCH v4 14/15] drm/bridge: tc358767: Drop unnecessary 8 byte buffer

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Message-ID: <34b09b98-0770-dec0-94cf-33138c3fb9ec@samsung.com>
Date:   Fri, 7 Jun 2019 08:41:18 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Andrey Smirnov <andrew.smirnov@...il.com>,
        dri-devel@...ts.freedesktop.org
Cc:     Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Andrey Gusakov <andrey.gusakov@...entembedded.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Cory Tusar <cory.tusar@....aero>,
        Chris Healy <cphealy@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 14/15] drm/bridge: tc358767: Drop unnecessary 8 byte
 buffer

On 07.06.2019 06:45, Andrey Smirnov wrote:
> tc_get_display_props() never reads more than a byte via AUX, so
> there's no need to reserve 8 for that purpose. No function change
> intended.
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
Reviewed-by: Andrzej Hajda <a.hajda@...sung.com>

 --
Regards
Andrzej
> Cc: Andrzej Hajda <a.hajda@...sung.com>
> Cc: Laurent Pinchart <Laurent.pinchart@...asonboard.com>
> Cc: Tomi Valkeinen <tomi.valkeinen@...com>
> Cc: Andrey Gusakov <andrey.gusakov@...entembedded.com>
> Cc: Philipp Zabel <p.zabel@...gutronix.de>
> Cc: Cory Tusar <cory.tusar@....aero>
> Cc: Chris Healy <cphealy@...il.com>
> Cc: Lucas Stach <l.stach@...gutronix.de>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/gpu/drm/bridge/tc358767.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
> index e747f10021e3..4a245144aa83 100644
> --- a/drivers/gpu/drm/bridge/tc358767.c
> +++ b/drivers/gpu/drm/bridge/tc358767.c
> @@ -661,8 +661,7 @@ static int tc_aux_link_setup(struct tc_data *tc)
>  static int tc_get_display_props(struct tc_data *tc)
>  {
>  	int ret;
> -	/* temp buffer */
> -	u8 tmp[8];
> +	u8 reg;
>  
>  	/* Read DP Rx Link Capability */
>  	ret = drm_dp_link_probe(&tc->aux, &tc->link.base);
> @@ -678,21 +677,21 @@ static int tc_get_display_props(struct tc_data *tc)
>  		tc->link.base.num_lanes = 2;
>  	}
>  
> -	ret = drm_dp_dpcd_readb(&tc->aux, DP_MAX_DOWNSPREAD, tmp);
> +	ret = drm_dp_dpcd_readb(&tc->aux, DP_MAX_DOWNSPREAD, &reg);
>  	if (ret < 0)
>  		goto err_dpcd_read;
> -	tc->link.spread = tmp[0] & DP_MAX_DOWNSPREAD_0_5;
> +	tc->link.spread = reg & DP_MAX_DOWNSPREAD_0_5;
>  
> -	ret = drm_dp_dpcd_readb(&tc->aux, DP_MAIN_LINK_CHANNEL_CODING, tmp);
> +	ret = drm_dp_dpcd_readb(&tc->aux, DP_MAIN_LINK_CHANNEL_CODING, &reg);
>  	if (ret < 0)
>  		goto err_dpcd_read;
>  
>  	tc->link.scrambler_dis = false;
>  	/* read assr */
> -	ret = drm_dp_dpcd_readb(&tc->aux, DP_EDP_CONFIGURATION_SET, tmp);
> +	ret = drm_dp_dpcd_readb(&tc->aux, DP_EDP_CONFIGURATION_SET, &reg);
>  	if (ret < 0)
>  		goto err_dpcd_read;
> -	tc->link.assr = tmp[0] & DP_ALTERNATE_SCRAMBLER_RESET_ENABLE;
> +	tc->link.assr = reg & DP_ALTERNATE_SCRAMBLER_RESET_ENABLE;
>  
>  	dev_dbg(tc->dev, "DPCD rev: %d.%d, rate: %s, lanes: %d, framing: %s\n",
>  		tc->link.base.revision >> 4, tc->link.base.revision & 0x0f,