linux-kernel - Re: [PATCH v2 1/2] mmc: sdhci-pci-gli: GL9755: Support for CD/WP inversion on OF platforms

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Message-ID: <d3b93b6c-0f55-8c0f-0bd3-f6a090b358af@arm.com>
Date:   Mon, 13 Dec 2021 11:45:27 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Hector Martin <marcan@...can.st>,
        Ben Chuang <benchuanggli@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Sven Peter <sven@...npeter.dev>, Marc Zyngier <maz@...nel.org>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/2] mmc: sdhci-pci-gli: GL9755: Support for CD/WP
 inversion on OF platforms

On 2021-12-12 07:02, Hector Martin wrote:
> This is required on some Apple ARM64 laptops using this controller.
> As is typical on DT platforms, pull these quirks from the device tree
> using the standard mmc bindings.
> 
> See Documentation/devicetree/bindings/mmc/mmc-controller.yaml
> 
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
>   drivers/mmc/host/sdhci-pci-gli.c | 19 +++++++++++++++++--
>   1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
> index 4fd99c1e82ba..ad742743a494 100644
> --- a/drivers/mmc/host/sdhci-pci-gli.c
> +++ b/drivers/mmc/host/sdhci-pci-gli.c
> @@ -12,6 +12,7 @@
>   #include <linux/pci.h>
>   #include <linux/mmc/mmc.h>
>   #include <linux/delay.h>
> +#include <linux/of.h>
>   #include "sdhci.h"
>   #include "sdhci-pci.h"
>   #include "cqhci.h"
> @@ -114,8 +115,10 @@
>   #define   GLI_9755_WT_EN_OFF    0x0
>   
>   #define PCI_GLI_9755_PECONF   0x44
> -#define   PCI_GLI_9755_LFCLK    GENMASK(14, 12)
> -#define   PCI_GLI_9755_DMACLK   BIT(29)
> +#define   PCI_GLI_9755_LFCLK          GENMASK(14, 12)
> +#define   PCI_GLI_9755_DMACLK         BIT(29)
> +#define   PCI_GLI_9755_INVERT_CD      BIT(30)
> +#define   PCI_GLI_9755_INVERT_WP      BIT(31)
>   
>   #define PCI_GLI_9755_CFG2          0x48
>   #define   PCI_GLI_9755_CFG2_L1DLY    GENMASK(28, 24)
> @@ -570,6 +573,18 @@ static void gl9755_hw_setting(struct sdhci_pci_slot *slot)
>   	gl9755_wt_on(pdev);
>   
>   	pci_read_config_dword(pdev, PCI_GLI_9755_PECONF, &value);
> +#ifdef CONFIG_OF
> +	if (pdev->dev.of_node) {

FWIW, of_property_read_bool() should handle a NULL node correctly, and 
its stub be optimised away for !OF, so you don't really need the 
explicit check or the #ifdef.

Robin.

> +		/*
> +		 * Apple ARM64 platforms using these chips may have
> +		 * inverted CD/WP detection.
> +		 */
> +		if (of_property_read_bool(pdev->dev.of_node, "cd-inverted"))
> +			value |= PCI_GLI_9755_INVERT_CD;
> +		if (of_property_read_bool(pdev->dev.of_node, "wp-inverted"))
> +			value |= PCI_GLI_9755_INVERT_WP;
> +	}
> +#endif
>   	value &= ~PCI_GLI_9755_LFCLK;
>   	value &= ~PCI_GLI_9755_DMACLK;
>   	pci_write_config_dword(pdev, PCI_GLI_9755_PECONF, value);
>