linux-kernel - Re: [PATCH] media: tw5864: Simplify 'tw5864

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Date:   Tue, 19 Oct 2021 19:46:55 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Kieran Bingham <kieran.bingham@...asonboard.com>,
        andrey.utkin@...p.bluecherry.net, anton@...p.bluecherry.net,
        maintainers@...echerrydvr.com, mchehab@...nel.org
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] media: tw5864: Simplify 'tw5864_finidev()'

Le 19/10/2021 à 12:35, Kieran Bingham a écrit :
> Quoting Christophe JAILLET (2021-10-16 09:40:29)
>> Some resources are allocated with 'pci_request_regions()', so use
>> 'pci_release_regions()' to free them, instead of a verbose
>> 'release_mem_region()'.
> 
> And the driver was even already using pci_release_regions() in
> tw5864_initdev(), so indeed this makes it more consistent too.
> 
> I'm curious that tw5864_initdev() calls pci_enable_device() (and
> pci_disable_device in it's error path), while tw5864_finidev() doesn't.

I agree with you. I should have spotted it when I've looked at the probe 
and remove functions :(

> 
> Would you like to submit a patch to fix that on top of this one? or should I?

Either way is fine for me.
If it's fine for you to fix it, I leave it to you.

A more invasive fix could be to switch to 'pcim_enable_device()' and 
remove both 'pci_release_regions()' and 'pci_disable_device()' calls.

CJ

> 
> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> 
>> There is no point in calling 'devm_kfree()'. The corresponding resource is
>> managed, so it will be fried automatically.
> 
> Indeed.
> 
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>> ---
>>   drivers/media/pci/tw5864/tw5864-core.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/pci/tw5864/tw5864-core.c b/drivers/media/pci/tw5864/tw5864-core.c
>> index 23d3cae54a5d..fee3b7711901 100644
>> --- a/drivers/media/pci/tw5864/tw5864-core.c
>> +++ b/drivers/media/pci/tw5864/tw5864-core.c
>> @@ -333,11 +333,9 @@ static void tw5864_finidev(struct pci_dev *pci_dev)
>>   
>>          /* release resources */
>>          iounmap(dev->mmio);
>> -       release_mem_region(pci_resource_start(pci_dev, 0),
>> -                          pci_resource_len(pci_dev, 0));
>> +       pci_release_regions(pci_dev);
>>   
>>          v4l2_device_unregister(&dev->v4l2_dev);
>> -       devm_kfree(&pci_dev->dev, dev);
>>   }
>>   
>>   static struct pci_driver tw5864_pci_driver = {
>> -- 
>> 2.30.2
>>
>