linux-kernel - Re: [PATCH 04/21] ata: libahci_platform: Convert to using handy devm-ioremap methods

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Date:   Wed, 6 Apr 2022 23:42:34 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Hans de Goede <hdegoede@...hat.com>,
        Jens Axboe <axboe@...nel.dk>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Rob Herring <robh+dt@...nel.org>, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 04/21] ata: libahci_platform: Convert to using handy
 devm-ioremap methods

On Thu, Mar 24, 2022 at 10:11:09AM +0900, Damien Le Moal wrote:
> On 3/24/22 09:16, Serge Semin wrote:
> > Currently the IOMEM AHCI registers space is mapped by means of the
> > two functions invocation: platform_get_resource() is used to get the very
> > first memory resource and devm_ioremap_resource() is called to remap that
> > resource. Device-managed kernel API provides a handy wrapper to perform
> > the same in single function call: devm_platform_ioremap_resource().
> 
> > 
> > While at it seeing many AHCI platform drivers rely on having the AHCI CSR
> > space marked with "ahci" name let's first try to find and remap the CSR
> > IO-mem with that name and only if it fails fallback to getting the very
> > first registers space platform resource.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> > ---
> >  drivers/ata/libahci_platform.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> > index 1bd2f1686239..8eabbb5f208c 100644
> > --- a/drivers/ata/libahci_platform.c
> > +++ b/drivers/ata/libahci_platform.c
> > @@ -404,11 +404,13 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
> >  
> >  	devres_add(dev, hpriv);
> >  
> > -	hpriv->mmio = devm_ioremap_resource(dev,
> > -			      platform_get_resource(pdev, IORESOURCE_MEM, 0));
> > +	hpriv->mmio = devm_platform_ioremap_resource_byname(pdev, "ahci");
> 

> See __devm_ioremap_resource(): if there is no resource named "ahci" found,
> then this will print an error message ("invalid resource\n"). That may
> confuse users as this error message was not present before. So you may
> want to change this code to something like this:

Right. I should have checked that the method can print an error
message in the log. Thanks for the heads-up. I'll fix the patch as you
suggest. It's a pity there is no an alternative with "_optional"
semantics though.

-Sergey

> 
> /*
>  * If the DT provided an "ahci" named resource, use it. Otherwise,
>  * fallback to using the default first resource for the device node.
>  */
> if (platform_get_resource_byname(pdev, IORESOURCE_MEM, "ahci"))
> 	hpriv->mmio = devm_platform_ioremap_resource_byname(pdev, "ahci");
> else
> 	hpriv->mmio = devm_platform_ioremap_resource(pdev, 0);
> if (IS_ERR(hpriv->mmio)) {
> 	rc = PTR_ERR(hpriv->mmio);
> 	goto err_out;
> }
> 
> >  	if (IS_ERR(hpriv->mmio)) {
> > -		rc = PTR_ERR(hpriv->mmio);
> > -		goto err_out;
> > +		hpriv->mmio = devm_platform_ioremap_resource(pdev, 0);
> > +		if (IS_ERR(hpriv->mmio)) {
> > +			rc = PTR_ERR(hpriv->mmio);
> > +			goto err_out;
> > +		}
> >  	}
> >  
> >  	for (i = 0; i < AHCI_MAX_CLKS; i++) {
> 
> 
> -- 
> Damien Le Moal
> Western Digital Research