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Subject: Re: [PATCH] drm/bridge/synopsys: dsi: readl_poll_timeout return
 value clean up
To:     Philippe CORNU <philippe.cornu@st.com>,
        Archit Taneja <architt@codeaurora.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        David Airlie <airlied@linux.ie>,
        Brian Norris <briannorris@chromium.org>,
        Benjamin Gaignard <benjamin.gaignard@linaro.org>,
        Bhumika Goyal <bhumirks@gmail.com>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Sandy Huang <hjc@rock-chips.com>,
        Heiko Stubner <heiko@sntech.de>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-rockchip@lists.infradead.org" 
        <linux-rockchip@lists.infradead.org>
Cc:     Yannick FERTRE <yannick.fertre@st.com>,
        Vincent ABRIOU <vincent.abriou@st.com>,
        Alexandre TORGUE <alexandre.torgue@st.com>
From:   Andrzej Hajda <a.hajda@samsung.com>
Message-ID: <290c749a-70bf-2b74-1fb9-2de26708d001@samsung.com>
Date:   Fri, 2 Mar 2018 11:21:23 +0100
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On 01.03.2018 10:00, Philippe CORNU wrote:
> Hi Archit, Andrzej & Laurent,
>
> May I ask you please your feedback on this small patch?
> Many thanks,
>
> Philippe :-)
>
> On 02/04/2018 10:36 PM, Philippe Cornu wrote:
>> The readl_poll_timeout() return value is 0 in case of success
>> so it is better to detect errors without taking care of the
>> return value sign.
>>
>> Signed-off-by: Philippe Cornu <philippe.cornu@st.com>

The patch is of course correct. However I am not sure if necessary. For
sure functionally it does not change anything.
AFAIK kernel CodingStyle says nothing about it, so I suppose it is
matter of personal taste.
Anyway I can give it:
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

 --
Regards
Andrzej

>> ---
>>   drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> index 65aeb3f78b48..4d0e8471a15c 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> @@ -342,7 +342,7 @@ static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi *dsi, u32 hdr_val)
>>   	ret = qq(dsi->base + DSI_CMD_PKT_STATUS,
>>   				 val, !(val & GEN_CMD_FULL), 1000,
>>   				 CMD_PKT_STATUS_TIMEOUT_US);
>> -	if (ret < 0) {
>> +	if (ret) {
>>   		dev_err(dsi->dev, "failed to get available command FIFO\n");
>>   		return ret;
>>   	}
>> @@ -353,7 +353,7 @@ static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi *dsi, u32 hdr_val)
>>   	ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS,
>>   				 val, (val & mask) == mask,
>>   				 1000, CMD_PKT_STATUS_TIMEOUT_US);
>> -	if (ret < 0) {
>> +	if (ret) {
>>   		dev_err(dsi->dev, "failed to write command FIFO\n");
>>   		return ret;
>>   	}
>> @@ -385,7 +385,7 @@ static int dw_mipi_dsi_write(struct dw_mipi_dsi *dsi,
>>   		ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS,
>>   					 val, !(val & GEN_PLD_W_FULL), 1000,
>>   					 CMD_PKT_STATUS_TIMEOUT_US);
>> -		if (ret < 0) {
>> +		if (ret) {
>>   			dev_err(dsi->dev,
>>   				"failed to get available write payload FIFO\n");
>>   			return ret;
>> @@ -716,13 +716,13 @@ static void dw_mipi_dsi_dphy_enable(struct dw_mipi_dsi *dsi)
>>   
>>   	ret = readl_poll_timeout(dsi->base + DSI_PHY_STATUS, val,
>>   				 val & PHY_LOCK, 1000, PHY_STATUS_TIMEOUT_US);
>> -	if (ret < 0)
>> +	if (ret)
>>   		DRM_DEBUG_DRIVER("failed to wait phy lock state\n");
>>   
>>   	ret = readl_poll_timeout(dsi->base + DSI_PHY_STATUS,
>>   				 val, val & PHY_STOP_STATE_CLK_LANE, 1000,
>>   				 PHY_STATUS_TIMEOUT_US);
>> -	if (ret < 0)
>> +	if (ret)
>>   		DRM_DEBUG_DRIVER("failed to wait phy clk lane stop state\n");
>>   }
>>