[PATCH] ARM: mx3: Fix a race condition in mxcmmc

[Daniel Mack]

Sascha, can you take this to your tree?

On Tue, Apr 27, 2010 at 12:24:42PM +0200, Daniel Mack wrote:
> From cefcdab08d1c9636c4a7290bc2bbe937d051bce4 Mon Sep 17 00:00:00 2001
> From: Volker Ernst <volker.ernst at txtr.com>
> Date: Mon, 26 Apr 2010 22:51:07 +0200
> Subject: [PATCH] ARM: mx3: Fix a race condition in mxcmmc
> 
> This fixes a race condition regarding interrupt bits in the SDHC
> controller driver code.
> 
> In case of PIO-transfer it does not clear SDHC-status bit#11/12
> in the INT-handler anymore. INT-handler might be called during
> an ongoing PIO-data-transfer (with some other INT-flag set) and
> PIO-transfer depends on these bits being set to detect the end
> of the data-transfer. This also means that at the end of PIO-
> transfer that PIO-software has to clear these bits itself.
> 
> However in case of DMA-transfer these bits have to be cleared
> in the INT-handler, because they are used to generate INTs then.
> 
> Works solid, no more problems here, can transfer big files.
> 
> Signed-off-by: Volker Ernst <volker.ernst at txtr.com>
> Acked-by: Daniel Mack <daniel at caiaq.de>
> Cc: Andy Green <andy at warmcat.com>
> ---
>  drivers/mmc/host/mxcmmc.c |   13 ++++++++++++-
>  1 files changed, 12 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/mmc/host/mxcmmc.c b/drivers/mmc/host/mxcmmc.c
> index 2c53024..ec18e3b 100644
> --- a/drivers/mmc/host/mxcmmc.c
> +++ b/drivers/mmc/host/mxcmmc.c
> @@ -489,6 +489,9 @@ static void mxcmci_datawork(struct work_struct *work)
>  	struct mxcmci_host *host = container_of(work, struct mxcmci_host,
>  						  datawork);
>  	int datastat = mxcmci_transfer_data(host);
> +
> +	writel(STATUS_READ_OP_DONE | STATUS_WRITE_OP_DONE,
> +		host->base + MMC_REG_STATUS);
>  	mxcmci_finish_data(host, datastat);
>  
>  	if (host->req->stop) {
> @@ -553,7 +556,8 @@ static irqreturn_t mxcmci_irq(int irq, void *devid)
>  	u32 stat;
>  
>  	stat = readl(host->base + MMC_REG_STATUS);
> -	writel(stat & ~STATUS_SDIO_INT_ACTIVE, host->base + MMC_REG_STATUS);
> +	writel(stat & ~(STATUS_SDIO_INT_ACTIVE | STATUS_DATA_TRANS_DONE |
> +			STATUS_WRITE_OP_DONE), host->base + MMC_REG_STATUS);
>  
>  	dev_dbg(mmc_dev(host->mmc), "%s: 0x%08x\n", __func__, stat);
>  
> @@ -561,6 +565,13 @@ static irqreturn_t mxcmci_irq(int irq, void *devid)
>  	sdio_irq = (stat & STATUS_SDIO_INT_ACTIVE) && host->use_sdio;
>  	spin_unlock_irqrestore(&host->lock, flags);
>  
> +#ifdef HAS_DMA
> +	if (mxcmci_use_dma(host) &&
> +	    (stat & (STATUS_READ_OP_DONE | STATUS_WRITE_OP_DONE)))
> +		writel(STATUS_READ_OP_DONE | STATUS_WRITE_OP_DONE,
> +			host->base + MMC_REG_STATUS);
> +#endif
> +
>  	if (sdio_irq) {
>  		writel(STATUS_SDIO_INT_ACTIVE, host->base + MMC_REG_STATUS);
>  		mmc_signal_sdio_irq(host->mmc);
> -- 
> 1.7.0.3
> 
> 
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