Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 6 Oct 2020 15:58:30 +0300
From:   Sakari Ailus <sakari.ailus@iki.fi>
To:     David Lu <david.lu@bitland.com.cn>
Cc:     Dongchun Zhu <dongchun.zhu@mediatek.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] media: ov8856: decrease hs_trail time
Message-ID: <20201006125830.GD5682@valkosipuli.retiisi.org.uk>
References: <20200727030748.3791-1-david.lu@bitland.com.cn>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200727030748.3791-1-david.lu@bitland.com.cn>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk

Hi David,

On Mon, Jul 27, 2020 at 11:07:48AM +0800, David Lu wrote:
> To meet mipi hi speed transmission, decrease hs_trail time to pass mipi
> test.
> 
> Signed-off-by: David Lu <david.lu@bitland.com.cn>
> ---
>  drivers/media/i2c/ov8856.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
> index 4ca27675cc5a..1f1835b14a24 100644
> --- a/drivers/media/i2c/ov8856.c
> +++ b/drivers/media/i2c/ov8856.c
> @@ -284,7 +284,7 @@ static const struct ov8856_reg mode_3280x2464_regs[] = {
>  	{0x4601, 0x80},
>  	{0x4800, 0x44},
>  	{0x4816, 0x53},
> -	{0x481b, 0x58},
> +	{0x481b, 0x42},

Could you elaborate a little more in the commit message what does the
register do and exactly what is changed? Is it the raw ths_trail value or
something else?

The nature of the change is such that it is very likely board specific
somehow. If you change this value for your system, does the change have
adverse effects elsewhere?

>  	{0x481f, 0x27},
>  	{0x4837, 0x16},
>  	{0x483c, 0x0f},
> @@ -474,7 +474,7 @@ static const struct ov8856_reg mode_1640x1232_regs[] = {
>  	{0x4601, 0x80},
>  	{0x4800, 0x44},
>  	{0x4816, 0x53},
> -	{0x481b, 0x58},
> +	{0x481b, 0x42},
>  	{0x481f, 0x27},
>  	{0x4837, 0x16},
>  	{0x483c, 0x0f},

-- 
Kind regards,

Sakari Ailus