Re: [PATCH] Revert "mmc: dw_mmc: Add check for IDMAC configuration"

Girish K S
2012-09-11T03:47:00Z

On 11 September 2012 07:53, Seungwon Jeon <tgih.jun@samsung.com> wrote:
> This reverts commit 94c6cee91(Add check for IDMAC configuration).
> Synopsys says that only if internal dmac is not present, optional
> external dma interface is present. When internal dmac is present,
> '0' value in DMA_INTERFACE of HCON is reasonable. DMA_INTERFACE
> indicates external dma interface. And idmac initialization is
> prohibited now. So, let's revert this commit.

There is no register, or a field in any register which says IDMAC present.
I can see only use_idmac bit field in CTRL register.
So in first place how will i know whether IDMAC is present? Have you
assumed that IDMAC is present.
I would like to know without assuming, whether IDMAC is present.
If i have missed out something let me know. i will check and revert back

>
> CC: Girish K S <girish.shivananjappa@linaro.org>
> Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
> ---
> drivers/mmc/host/dw_mmc.c | 15 ++-------------
> 1 files changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 36f98c0..dcbe9aa 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -405,23 +405,11 @@ static void dw_mci_idmac_start_dma(struct dw_mci *host, unsigned int sg_len)
> static int dw_mci_idmac_init(struct dw_mci *host)
> {
> struct idmac_desc *p;
> - int i, dma_support;
> + int i;
>
> /* Number of descriptors in the ring buffer */
> host->ring_size = PAGE_SIZE / sizeof(struct idmac_desc);
>
> - /* Check if Hardware Configuration Register has support for DMA */
> - dma_support = (mci_readl(host, HCON) >> 16) & 0x3;
> -
> - if (!dma_support || dma_support > 2) {
> - dev_err(&host->dev,
> - "Host Controller does not support IDMA Tx.\n");
> - host->dma_ops = NULL;
> - return -ENODEV;
> - }
> -
> - dev_info(&host->dev, "Using internal DMA controller.\n");
> -
> /* Forward link the descriptor list */
> for (i = 0, p = host->sg_cpu; i < host->ring_size - 1; i++, p++)
> p->des3 = host->sg_dma + (sizeof(struct idmac_desc) * (i + 1));
> @@ -1895,6 +1883,7 @@ static void dw_mci_init_dma(struct dw_mci *host)
> /* Determine which DMA interface to use */
> #ifdef CONFIG_MMC_DW_IDMAC
> host->dma_ops = &dw_mci_idmac_ops;
> + dev_info(&host->dev, "Using internal DMA controller.\n");
> #endif
>
> if (!host->dma_ops)
> --
> 1.7.0.4
>
>