Subject: [PATCH] mmc: atmel-mci: fix burst/chunk size modification

From: [email-masked] (Chris Ball)
Date: Wed, 06 Jun 2012 06:06:43 -0400

Hi,

On Wed, May 16 2012, ludovic.desroches at atmel.com wrote:
> From: Nicolas Ferre <[email-masked]>
>
> The use of DMA slave config operation requires that the burst size
> (aka chunk size) is specified through this interface.
> Modify atmel-mci slave driver to use this specification on its side.
>
> Signed-off-by: Nicolas Ferre <[email-masked]>
> Signed-off-by: Ludovic Desroches <[email-masked]> 
> ---
>  drivers/mmc/host/atmel-mci-regs.h |   14 ++++++++++++++
>  drivers/mmc/host/atmel-mci.c      |    7 +++++--
>  2 files changed, 19 insertions(+), 2 deletions(-)

This doesn't apply:

> diff --git a/drivers/mmc/host/atmel-mci-regs.h b/drivers/mmc/host/atmel-mci-regs.h
> index 787aba1..ab56f7d 100644
> --- a/drivers/mmc/host/atmel-mci-regs.h
> +++ b/drivers/mmc/host/atmel-mci-regs.h
> @@ -140,4 +140,18 @@
>  #define atmci_writel(port,reg,value)			\
>  	__raw_writel((value), (port)->regs + reg)
>  
> +/*
> + * Fix sconfig's burst size according to atmel MCI. We need to convert them as:
> + * 1 -> 0, 4 -> 1, 8 -> 2, 16 -> 3.
> + *
> + * This can be done by finding most significant bit set.
> + */
> +static inline unsigned int atmci_convert_chksize(unsigned int maxburst)
> +{
> +	if (maxburst > 1)
> +		return fls(maxburst) - 2;
> +	else
> +		return 0;
> +}
> +
>  #endif /* __DRIVERS_MMC_ATMEL_MCI_H__ */
> diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
> index 2dbfb28..50e8652 100644
> --- a/drivers/mmc/host/atmel-mci.c
> +++ b/drivers/mmc/host/atmel-mci.c
> @@ -834,6 +834,7 @@ atmci_prepare_data_dma(struct atmel_mci *host, struct mmc_data *data)
>  	enum dma_data_direction		direction;
>  	enum dma_transfer_direction	slave_dirn;
>  	unsigned int			sglen;
> +	u32				maxburst;
>  	u32 iflags;
>  
>  	data->error = -EINPROGRESS;
> @@ -867,16 +868,18 @@ atmci_prepare_data_dma(struct atmel_mci *host, struct mmc_data *data)
>  	if (!chan)
>  		return -ENODEV;
>  
> -	atmci_writel(host, ATMCI_DMA, ATMCI_DMA_CHKSIZE(3) | ATMCI_DMAEN);
> -

.. because mainline actually looks like:

	if (host->caps.has_dma)
		atmci_writel(host, ATMCI_DMA, ATMCI_DMA_CHKSIZE(3) | ATMCI_DMAEN);

and has done since 2011-08-11.  Maybe this was created against the wrong
kernel version -- want to resend?

>  	if (data->flags & MMC_DATA_READ) {
>  		direction = DMA_FROM_DEVICE;
>  		host->dma_conf.direction = slave_dirn = DMA_DEV_TO_MEM;
> +		maxburst = atmci_convert_chksize(host->dma_conf.src_maxburst);
>  	} else {
>  		direction = DMA_TO_DEVICE;
>  		host->dma_conf.direction = slave_dirn = DMA_MEM_TO_DEV;
> +		maxburst = atmci_convert_chksize(host->dma_conf.dst_maxburst);
>  	}
>  
> +	atmci_writel(host, ATMCI_DMA, ATMCI_DMA_CHKSIZE(maxburst) | ATMCI_DMAEN);
> +
>  	sglen = dma_map_sg(chan->device->dev, data->sg,
>  			data->sg_len, direction);

Thanks,

- Chris.
-- 
Chris Ball   <[email-masked]>   <http://printf.net/>
One Laptop Per Child