linux-kernel - Re: [PATCH 2/2] MMC: P2020 SDHC: Fix bug when writing to SDHCI_HOST

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Date:	Thu, 13 Jun 2013 11:21:14 -0700
From:	Anton Vorontsov <anton@...msg.org>
To:	Oded Gabbay <ogabbay@...aoptical.com>
Cc:	cjb@...top.org, Chang-Ming.Huang@...escale.com,
	gregkh@...uxfoundation.org, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] MMC: P2020 SDHC: Fix bug when writing to
 SDHCI_HOST_CONTROL register

On Wed, Jun 12, 2013 at 04:54:37PM +0300, Oded Gabbay wrote:
> The P2020 has a non-standard implementation of the SDHCI_HOST_CONTROL
> register. This patch adds a QUIRK in the SDHCI header to signal that
> a host controller has a non-standard SDHCI_HOST_CONTROL register. The
> patch adds a check to the function esdhc_writeb in file
> sdhci-of-esdhc.c, where it checks if the write is done to the
> SDHCI_HOST_CONTROL register and th host has the above mentioned QUIRK,
> then the function simply returns instead of writing to the register.
> The patch also detects if the processor is P2020 (by looking in dev
> tree) and if so, adds the QUIRK to the host->quirk2
> 
> This patch depends on the first patch of this set (total of 2 patches)
> 
> Signed-off-by: Oded Gabbay <ogabbay@...aoptical.com>
> ---
>  drivers/mmc/host/sdhci-of-esdhc.c | 14 ++++++++++++++
>  include/linux/mmc/sdhci.h         |  2 ++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
> index fd149a0..ca88529 100644
> --- a/drivers/mmc/host/sdhci-of-esdhc.c
> +++ b/drivers/mmc/host/sdhci-of-esdhc.c
> @@ -121,6 +121,11 @@ static void esdhc_writeb(struct sdhci_host *host, u8 val, int reg)
>  	if (reg == SDHCI_HOST_CONTROL) {
>  		u32 dma_bits;
>  
> +		/* If host control register is not standard, exit
> +		 * this function */

Broken comments.

> +		if (host->quirks2 & SDHCI_QUIRK2_BROKEN_HOST_CONTROL)
> +			return;
> +
>  		/* DMA select is 22,23 bits in Protocol Control Register */
>  		dma_bits = (val & SDHCI_CTRL_DMA_MASK) << 5;
>  		clrsetbits_be32(host->ioaddr + reg , SDHCI_CTRL_DMA_MASK << 5,
> @@ -289,6 +294,7 @@ static const struct sdhci_pltfm_data sdhci_esdhc_pdata = {
>  static int sdhci_esdhc_probe(struct platform_device *pdev)
>  {
>  	struct sdhci_host *host;
> +	struct device_node *np;
>  	int ret = 0;
>  
>  	host = sdhci_pltfm_init(pdev, &sdhci_esdhc_pdata);
> @@ -297,6 +303,14 @@ static int sdhci_esdhc_probe(struct platform_device *pdev)
>  
>  	sdhci_get_of_property(pdev);
>  
> +	np = pdev->dev.of_node;
> +	if (of_device_is_compatible(np, "fsl,p2020-esdhc")) {
> +		/* Freescale messed up with P2020 as it has a non-standard
> +		* host control register
> +		*/

Ditto.

Otherwise, it looks good. Thanks!

Reviewed-by: Anton Vorontsov <anton@...msg.org>

> +		host->quirks2 |= SDHCI_QUIRK2_BROKEN_HOST_CONTROL;
> +	}
> +
>  	/* call to generic mmc_of_parse to support additional capabilities */
>  	mmc_of_parse(host->mmc);
>  
> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> index b838ffc..b73dbdd 100644
> --- a/include/linux/mmc/sdhci.h
> +++ b/include/linux/mmc/sdhci.h
> @@ -95,6 +95,8 @@ struct sdhci_host {
>  /* The system physically doesn't support 1.8v, even if the host does */
>  #define SDHCI_QUIRK2_NO_1_8_V				(1<<2)
>  #define SDHCI_QUIRK2_PRESET_VALUE_BROKEN		(1<<3)
> +/* Controller has a non-standard host control register */
> +#define SDHCI_QUIRK2_BROKEN_HOST_CONTROL		(1<<4)
>  
>  	int irq;		/* Device IRQ */
>  	void __iomem *ioaddr;	/* Mapped address */
> -- 
> 1.8.3.1
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