linux-kernel - Re: [PATCH 1/2] media: s5p-mfc: check for firmware allocation before requesting firmware

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Date:   Thu, 2 Nov 2017 18:23:54 -0600
From:   Shuah Khan <shuahkh@....samsung.com>
To:     Andrzej Hajda <a.hajda@...sung.com>, kyungmin.park@...sung.com,
        kamil@...as.org, jtp.park@...sung.com, mchehab@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH 1/2] media: s5p-mfc: check for firmware allocation before
 requesting firmware

On 11/02/2017 02:12 AM, Andrzej Hajda wrote:
> Hi Shuah,
> 
> On 06.10.2017 23:30, Shuah Khan wrote:
>> Check if firmware is allocated before requesting firmware instead of
>> requesting firmware only to release it if firmware is not allocated.
>>
>> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
>> ---
>>  drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c | 10 +++++-----
>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c b/drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c
>> index 69ef9c2..f064a0d1 100644
>> --- a/drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c
>> +++ b/drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c
>> @@ -55,6 +55,11 @@ int s5p_mfc_load_firmware(struct s5p_mfc_dev *dev)
>>  	 * into kernel. */
>>  	mfc_debug_enter();
>>  
>> +	if (!dev->fw_buf.virt) {
>> +		mfc_err("MFC firmware is not allocated\n");
>> +		return -EINVAL;
>> +	}
>> +
>>  	for (i = MFC_FW_MAX_VERSIONS - 1; i >= 0; i--) {
>>  		if (!dev->variant->fw_name[i])
>>  			continue;
>> @@ -75,11 +80,6 @@ int s5p_mfc_load_firmware(struct s5p_mfc_dev *dev)
>>  		release_firmware(fw_blob);
>>  		return -ENOMEM;
>>  	}
>> -	if (!dev->fw_buf.virt) {
>> -		mfc_err("MFC firmware is not allocated\n");
>> -		release_firmware(fw_blob);
>> -		return -EINVAL;
>> -	}
> 
> Is there any scenario in which dev->fw_buf.virt is null and
> s5p_mfc_load_firmware is called?
> I suspect this check is not necessary at all.
> 

I don't believe so. Allocation is done in s5p_mfc_configure_dma_memory()
code path and if that fails it bails out of _probe. I can remove the check
all together.

thanks,
-- Shuah