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

From: [email-masked] (ludovic.desroches)
Date: Thu, 24 May 2012 09:21:00 +0200

Hi Chris,

I was doing some tests on mmc-next and I had issues with atmel-mci and 
DMA because this patch was missing.

Can you pull it?

Thanks.

Regards.

Ludovic

Le 05/16/2012 04:00 PM, ludovic.desroches at atmel.com a ?crit :
> 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(-)
>
> 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);
> -
>   	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);
>