[PATCH 3/4] mmc: sunxi: Reset behavior fix
Hans de Goede
hdegoede at redhat.com
Tue Dec 16 01:57:10 PST 2014
On 16-12-14 01:37, David Lanzendörfer wrote:
> When there is only one DES available the DMA performs a FIFO reset and waits until the reinitialization has been completed.
> Disabling the SDXC_IDMAC_DES0_DIC bit prevents the DMA from sending an interrupt after it has finished this reinitialization.
> The flags SDXC_IDMAC_DES0_FD and SDXC_IDMAC_DES0_LD are both required in order to use the controller with more than one DES.
> Signed-off-by: David Lanzendörfer <david.lanzendoerfer at o2s.ch>
> Reported-by: 李想 <lixiang at allwinnertech.com>
> drivers/mmc/host/sunxi-mmc.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> index 50bd3d2..5331c88 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -310,7 +310,17 @@ static void sunxi_mmc_init_idma_des(struct sunxi_mmc_host *host,
> pdes.config |= SDXC_IDMAC_DES0_FD;
> - pdes[i - 1].config = SDXC_IDMAC_DES0_OWN | SDXC_IDMAC_DES0_LD;
> + /*
> + * When there is only one DES available the DMA performs a FIFO reset and waits
> + * until the reinitialization has been completed.
> + * Disabling the SDXC_IDMAC_DES0_DIC bit prevents the DMA from sending an interrupt
> + * after it has finished this reinitialization.
> + */
> + pdes[i - 1].config = SDXC_IDMAC_DES0_OWN;
> + pdes[i - 1].config |= SDXC_IDMAC_DES0_FD;
> + pdes[i - 1].config |= SDXC_IDMAC_DES0_LD;
> + pdes[i - 1].config &= ~SDXC_IDMAC_DES0_DIC;
> * Avoid the io-store starting the idmac hitting io-mem before the
This is wrong. For one you are starting with an assignment, so you could just as well
set all the flags you want with a single line / assignment. Besides that you're setting
the FD flag, which should only be set for the first descriptor of a transfer, so for
multi descriptor transfers this is wrong.
Please see the patch which I send you which gets this right.
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