Re: [PATCH 5/5] PCI: iproc: Properly handle optional PHYs

[Andrew Murray <andrew.murray@arm.com>]

On Wed, Aug 28, 2019 at 06:36:36PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> devm_phy_get() can fail for a number of resides besides probe deferral.
> It can for example return -ENOMEM if it runs out of memory as it tries
> to allocate devres structures. Propagating only -EPROBE_DEFER is
> problematic because it results in these legitimately fatal errors being
> treated as "PHY not specified in DT".
> 
> What we really want is to ignore the optional PHYs only if they have not
> been specified in DT. devm_phy_optional_get() is a function that exactly
> does what's required here, so use that instead.
> 
> Cc: Ray Jui <rjui@broadcom.com>
> Cc: Scott Branden <sbranden@broadcom.com>
> Cc: bcm-kernel-feedback-list@broadcom.com
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/pci/controller/pcie-iproc-platform.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-iproc-platform.c b/drivers/pci/controller/pcie-iproc-platform.c
> index 5a3550b6bb29..9ee6200a66f4 100644
> --- a/drivers/pci/controller/pcie-iproc-platform.c
> +++ b/drivers/pci/controller/pcie-iproc-platform.c
> @@ -93,12 +93,9 @@ static int iproc_pcie_pltfm_probe(struct platform_device *pdev)
>  	pcie->need_ib_cfg = of_property_read_bool(np, "dma-ranges");
>  
>  	/* PHY use is optional */
> -	pcie->phy = devm_phy_get(dev, "pcie-phy");
> -	if (IS_ERR(pcie->phy)) {
> -		if (PTR_ERR(pcie->phy) == -EPROBE_DEFER)
> -			return -EPROBE_DEFER;
> -		pcie->phy = NULL;
> -	}
> +	pcie->phy = devm_phy_optional_get(dev, "pcie-phy");
> +	if (IS_ERR(pcie->phy))
> +		return PTR_ERR(pcie->phy);

Once you've applied Bjorn's feedback you can add:

Reviewed-by: Andrew Murray <andrew.murray@arm.com>

I initially thought that you forgot to check for -ENODEV - though I can see
that the implementation of devm_phy_optional_get very helpfully does this for
us and returns NULL instead of an error.

What is also confusing is that devm_regulator_get_optional, despite its
_optional suffix doesn't do this and returns an error. I wonder if
devm_phy_optional_get should be changed to return NULL instead of an error
instead of -ENODEV. I've copied Liam/Mark for feedback.

Thanks,

Andrew Murray

>  
>  	ret = devm_of_pci_get_host_bridge_resources(dev, 0, 0xff, &resources,
>  						    &iobase);
> -- 
> 2.22.0
>