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

Serge Semin
2022-04-06T21:31:37Z

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@baikalelectronics.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