Re: [PATCH 3/8] mmc: sdhci-pxav2: add register workaround for PXA168 silicon bug

[Adrian Hunter <adrian.hunter@intel.com>]

On 28/11/22 04:44, Doug Brown wrote:
> The PXA168 has a documented silicon bug that results in a data abort
> exception when accessing the SDHCI_HOST_VERSION register on SDH2 and
> SDH4 through a 16-bit read. Implement the workaround described in the
> errata, which performs a 32-bit read from a lower address instead. This
> is safe to use on all four SDH peripherals.
> 
> Signed-off-by: Doug Brown <doug@schmorgal.com>
> ---
>  drivers/mmc/host/sdhci-pxav2.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-pxav2.c b/drivers/mmc/host/sdhci-pxav2.c
> index 2f9fa0ecbddd..d76131b8986b 100644
> --- a/drivers/mmc/host/sdhci-pxav2.c
> +++ b/drivers/mmc/host/sdhci-pxav2.c
> @@ -80,6 +80,18 @@ static void pxav2_reset(struct sdhci_host *host, u8 mask)
>  	}
>  }
>  
> +static inline u16 pxav1_readw(struct sdhci_host *host, int reg)
> +{
> +	u32 temp;
> +	/* Workaround for data abort exception on SDH2 and SDH4 on PXA168 */
> +	if (reg == SDHCI_HOST_VERSION) {
> +		temp = readl(host->ioaddr + SDHCI_HOST_VERSION - 2) >> 16;
> +		return temp & 0xffff;

Isn't this the same as just:

		return readl(host->ioaddr + SDHCI_HOST_VERSION - 2) >> 16;

> +	}
> +
> +	return readw(host->ioaddr + reg);
> +}
> +
>  static void pxav2_mmc_set_bus_width(struct sdhci_host *host, int width)
>  {
>  	u8 ctrl;
> @@ -102,6 +114,7 @@ static void pxav2_mmc_set_bus_width(struct sdhci_host *host, int width)
>  }
>  
>  static const struct sdhci_ops pxav1_sdhci_ops = {
> +	.read_w        = pxav1_readw,
>  	.set_clock     = sdhci_set_clock,
>  	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
>  	.set_bus_width = pxav2_mmc_set_bus_width,