Re: [PATCH] mmc: sdhci-esdhc-imx: Fix SDIO interrupts

[Chris Ball <cjb@laptop.org>]

Hi Martin,

On Mon, Apr 15 2013, Martin Fuzzey wrote:
> Currently SDIO interrupts do not work on i.MX53 and maybe others.
>
> This was observed with a Marvell 8787 based SDIO wifi adapter
> using the mwifiex driver and firmware from the Marvell git
> repository.
> The symptom was a timeout after firmware download.
>
> Observing the SDIO_DAT1 line showed that an interrupt was requested
> (level 0) but no interrupt was generated in software, the line
> stayed low until a timeout ocurred and the card was reset.
>
> There is a Freescale errata
> 	ENGcm11186 "eSDHC misses SDIO interrupt when CINT is disabled"
>
> The workaround suggested by this errata is already implemented and
> involves clearing and then setting the D3CD bit in the host control
> register [see esdhc_writel_le()]
>
> However, when esdhc_writeb_le() is later used to write to
> SDHCI_HOST_CONTROL it always resets the D3CD bit.
>
> To fix this simply add the D3CD bit to the set of bits
> not modified by esdhc_writeb_le().
>
> Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
> ---
>  drivers/mmc/host/sdhci-esdhc-imx.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
> index 78ac002..3c4c63d 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -324,8 +324,10 @@ static void esdhc_writeb_le(struct sdhci_host *host, u8 val, int reg)
>  		/*
>  		 * Do not touch buswidth bits here. This is done in
>  		 * esdhc_pltfm_bus_width.
> +		 * Do not touch the D3CD bit either which is used for the
> +		 * SDIO interrupt errata workaround.
>  		 */
> -		mask = 0xffff & ~ESDHC_CTRL_BUSWIDTH_MASK;
> +		mask = 0xffff & ~(ESDHC_CTRL_BUSWIDTH_MASK | ESDHC_CTRL_D3CD);
>  
>  		esdhc_clrset_le(host, mask, new_val, reg);
>  		return;

I didn't see any review comments from other -imx developers -- I've
applied this to mmc-next now, hopefully someone will yell if there's
any reason not to.

Thanks,

- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child