On Thu, Oct 13, 2011 at 2:57 PM, Anton Staaf <robot...@chromium.org> wrote:
> Currently if a DMA buffer straddles a buffer alignment boundary
> (512KiB) then the DMA engine will pause and generate a DMA
> interrupt. Since the DMA interrupt is not enabled it will hang
> the MMC driver.
>
> This patch adds support for restarting the DMA transfer. The
> SYSTEM_ADDRESS register contains the next address that would have
> been read/written when a boundary is hit. So we can read that
> and write it back. The write triggers the resumption of the
> transfer.
>
> Signed-off-by: Anton Staaf <robot...@chromium.org>
> Cc: Tom Warren <twar...@nvidia.com>
> Cc: Stephen Warren <swar...@nvidia.com>
Adding Albert to CC.
-Anton
> ---
> drivers/mmc/tegra2_mmc.c | 15 +++++++++++----
> 1 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/tegra2_mmc.c b/drivers/mmc/tegra2_mmc.c
> index 8b6f829..195f89d 100644
> --- a/drivers/mmc/tegra2_mmc.c
> +++ b/drivers/mmc/tegra2_mmc.c
> @@ -256,9 +256,15 @@ static int mmc_send_cmd(struct mmc *mmc, struct mmc_cmd
> *cmd,
> __func__, mask);
> return -1;
> } else if (mask & (1 << 3)) {
> - /* DMA Interrupt */
> + /*
> + * DMA Interrupt, restart the transfer where
> + * it was interrupted.
> + */
> + unsigned int address =
> readl(&host->reg->sysad);
> +
> debug("DMA end\n");
> - break;
> + writel((1 << 3), &host->reg->norintsts);
> + writel(address, &host->reg->sysad);
> } else if (mask & (1 << 1)) {
> /* Transfer Complete */
> debug("r/w is done\n");
> @@ -442,12 +448,13 @@ static int mmc_core_init(struct mmc *mmc)
> * NORMAL Interrupt Status Enable Register init
> * [5] ENSTABUFRDRDY : Buffer Read Ready Status Enable
> * [4] ENSTABUFWTRDY : Buffer write Ready Status Enable
> + * [3] ENSTADMAINT : DMA Interrupt Status Enable
> * [1] ENSTASTANSCMPLT : Transfre Complete Status Enable
> * [0] ENSTACMDCMPLT : Command Complete Status Enable
> - */
> + */
> mask = readl(&host->reg->norintstsen);
> mask &= ~(0xffff);
> - mask |= (1 << 5) | (1 << 4) | (1 << 1) | (1 << 0);
> + mask |= (1 << 5) | (1 << 4) | (1 << 3) | (1 << 1) | (1 << 0);
> writel(mask, &host->reg->norintstsen);
>
> /*
> --
> 1.7.3.1
>
>
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot
