linux-kernel - Re: [PATCH 05/10] drm/tidss: Return error value from from softreset

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Message-ID: <b8851637-194c-4da7-beb6-fbe842f7788c@ideasonboard.com>
Date:   Thu, 2 Nov 2023 08:44:49 +0200
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Aradhya Bhatia <a-bhatia1@...com>,
        Devarsh Thakkar <devarsht@...com>,
        Jyri Sarha <jyri.sarha@....fi>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/10] drm/tidss: Return error value from from softreset

On 01/11/2023 15:59, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Wed, Nov 01, 2023 at 11:17:42AM +0200, Tomi Valkeinen wrote:
>> Return an error value from dispc_softreset() so that the caller can
>> handle the errors.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
>> ---
>>   drivers/gpu/drm/tidss/tidss_dispc.c | 17 ++++++++++++-----
>>   1 file changed, 12 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
>> index 9430625e2d62..cdbb88289082 100644
>> --- a/drivers/gpu/drm/tidss/tidss_dispc.c
>> +++ b/drivers/gpu/drm/tidss/tidss_dispc.c
>> @@ -2702,7 +2702,7 @@ static void dispc_init_errata(struct dispc_device *dispc)
>>   	}
>>   }
>>   
>> -static void dispc_softreset(struct dispc_device *dispc)
>> +static int dispc_softreset(struct dispc_device *dispc)
>>   {
>>   	u32 val;
>>   	int ret;
>> @@ -2712,8 +2712,12 @@ static void dispc_softreset(struct dispc_device *dispc)
>>   	/* Wait for reset to complete */
>>   	ret = readl_poll_timeout(dispc->base_common + DSS_SYSSTATUS,
>>   				 val, val & 1, 100, 5000);
>> -	if (ret)
>> -		dev_warn(dispc->dev, "failed to reset dispc\n");
>> +	if (ret) {
>> +		dev_err(dispc->dev, "failed to reset dispc\n");
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>>   }
>>   
>>   int dispc_init(struct tidss_device *tidss)
>> @@ -2828,8 +2832,11 @@ int dispc_init(struct tidss_device *tidss)
>>   	tidss->dispc = dispc;
>>   
>>   	/* K2G display controller does not support soft reset */
>> -	if (feat->subrev != DISPC_K2G)
>> -		dispc_softreset(dispc);
>> +	if (feat->subrev != DISPC_K2G) {
>> +		r = dispc_softreset(dispc);
>> +		if (r)
>> +			return r;
> 
> tidss->dispc will be set in this case. Could that cause problems ?

Not at the moment, but better be safe. I'll move the reset a few lines 
higher.

  Tomi