Re: [PATCH v9 05/16] PCI: imx6: Using "linux,pci-domain" as slot ID

From: Lorenzo Pieralisi <lpieralisi@kernel.org>
To: Frank Li <Frank.Li@nxp.com>
Cc: manivannan.sadhasivam@linaro.org, bhelgaas@google.com,
	conor+dt@kernel.org, devicetree@vger.kernel.org,
	festevam@gmail.com, helgaas@kernel.org, hongxing.zhu@nxp.com,
	imx@lists.linux.dev, kernel@pengutronix.de,
	krzysztof.kozlowski+dt@linaro.org,
	krzysztof.kozlowski@linaro.org, kw@linux.com,
	l.stach@pengutronix.de, linux-arm-kernel@lists.infradead.org,
	linux-imx@nxp.com, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org, robh@kernel.org,
	s.hauer@pengutronix.de, shawnguo@kernel.org
Subject: Re: [PATCH v9 05/16] PCI: imx6: Using "linux,pci-domain" as slot ID
Date: Fri, 2 Feb 2024 13:12:41 +0100	[thread overview]
Message-ID: <ZbzcOarorCS1MPRc@lpieralisi> (raw)
In-Reply-To: <20240119171122.3057511-6-Frank.Li@nxp.com>

"PCI: imx6: Use "linux,pci-domain" as slot ID"

On Fri, Jan 19, 2024 at 12:11:11PM -0500, Frank Li wrote:
> Avoid use get slot id by compared with register physical address. If there
> are more than 2 slots, compared logic will become complex.
> 
> "linux,pci-domain" already exist at dts since commit:
> 	commit (c0b70f05c87f3b arm64: dts: imx8mq: use_dt_domains for pci node).
> 
> So it is safe to remove compare basic address code:
> 	...
> 	if (dbi_base->start == IMX8MQ_PCIE2_BASE_ADDR)
> 		imx6_pcie->controller_id = 1;

No it is not unless you magically update all firmware out
there in the field.

> 	...
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> 
> Notes:
>     Change from v7 to v8
>     - fixed comments
>     - Added Manivannan Sadhasivam's review tag
>     Change from v5 to v7
>     - none
>     Change from v3 to v4
>     - remove compare basic address logic
>     Change from v2 to v3
>     - none
>     Change from v1 to v2
>     - fix of_get_pci_domain_nr return value check logic
> 
>  drivers/pci/controller/dwc/pci-imx6.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index eda6bc6ef80ee..773411d20329f 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -33,6 +33,7 @@
>  #include <linux/pm_domain.h>
>  #include <linux/pm_runtime.h>
>  
> +#include "../../pci.h"
>  #include "pcie-designware.h"
>  
>  #define IMX8MQ_GPR_PCIE_REF_USE_PAD		BIT(9)
> @@ -40,7 +41,6 @@
>  #define IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE	BIT(11)
>  #define IMX8MQ_GPR_PCIE_VREG_BYPASS		BIT(12)
>  #define IMX8MQ_GPR12_PCIE2_CTRL_DEVICE_TYPE	GENMASK(11, 8)
> -#define IMX8MQ_PCIE2_BASE_ADDR			0x33c00000
>  
>  #define to_imx6_pcie(x)	dev_get_drvdata((x)->dev)
>  
> @@ -1279,13 +1279,17 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  					     "Failed to get PCIEPHY reset control\n");
>  	}
>  
> -	switch (imx6_pcie->drvdata->variant) {
> -	case IMX7D:
> -		if (dbi_base->start == IMX8MQ_PCIE2_BASE_ADDR)
> -			imx6_pcie->controller_id = 1;
> -	default:
> -		break;
> -	}
> +	/* Using linux,pci-domain as PCI slot id */
> +	imx6_pcie->controller_id = of_get_pci_domain_nr(node);
> +	/*
> +	 * If there are no "linux,pci-domain" property specified in DT, then assume only one
> +	 * controller is available.
> +	 */
> +	if (imx6_pcie->controller_id == -EINVAL)
> +		imx6_pcie->controller_id = 0;

See above, this breaks compatibility with old DTs (and -EINVAL is not
the only error code you should handle).

Lorenzo

> +	else if (imx6_pcie->controller_id < 0)
> +		return dev_err_probe(dev, imx6_pcie->controller_id,
> +				     "linux,pci-domain have wrong value\n");
>  
>  	/* Grab turnoff reset */
>  	imx6_pcie->turnoff_reset = devm_reset_control_get_optional_exclusive(dev, "turnoff");
> -- 
> 2.34.1
> 