linux-kernel - Re: [PATCH v4 04/11] drm/bridge: it6505: fix aux command write to aux operaction register

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Message-ID: <daa103bd-d70f-460f-8ecd-88da9da0eb03@collabora.com>
Date: Thu, 26 Sep 2024 10:10:45 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Hermes Wu <Hermes.Wu@....com.tw>
Cc: Kenneth Hung <Kenneth.hung@....com.tw>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Allen Chen <allen.chen@....com.tw>,
 "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 04/11] drm/bridge: it6505: fix aux command write to aux
 operaction register

Il 26/09/24 09:47, Hermes Wu ha scritto:
> From: Hermes Wu <Hermes.wu@....com.tw>
> 
> The aux control register command is 4 bits LSB only, adding a MACRO to get
> correct operaction command.
> 
> Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
> Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
> ---
>   drivers/gpu/drm/bridge/ite-it6505.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 0583abdca75f..d1f5220e04a6 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -329,6 +329,8 @@ enum aux_cmd_type {
>   	CMD_AUX_GET_KSV_LIST = 0x10,
>   };
>   
> +#define GET_AUX_CONTROL_CODE(cmd) ((cmd) & 0x0F)

Just (cmd & 0xf) as the leading zero is meaningless.

As a out-of-scope consideration, though, this driver would really benefit from
a conversion to use bitfield macros... would be a nice cleanup.

Cheers,
Angelo

> +
>   enum aux_cmd_reply {
>   	REPLY_ACK,
>   	REPLY_NACK,
> @@ -1000,7 +1002,7 @@ static ssize_t it6505_aux_operation(struct it6505 *it6505,
>   				  size);
>   
>   	/* Aux Fire */
> -	it6505_write(it6505, REG_AUX_CMD_REQ, cmd);
> +	it6505_write(it6505, REG_AUX_CMD_REQ, GET_AUX_CONTROL_CODE(cmd));
>   
>   	ret = it6505_aux_wait(it6505);
>   	if (ret < 0)