On 12 June 2012 15:14, Will Newton <will.newton@xxxxxxxxx> wrote: > On Tue, Jun 12, 2012 at 10:40 AM, Girish K S > <girish.shivananjappa@xxxxxxxxxx> wrote: >> On 12 June 2012 15:05, Will Newton <will.newton@xxxxxxxxx> wrote: >>> On Tue, Jun 12, 2012 at 10:01 AM, Girish K S >>> <girish.shivananjappa@xxxxxxxxxx> wrote: >>>> On 12 June 2012 14:25, Will Newton <will.newton@xxxxxxxxx> wrote: >>>>> On Tue, Jun 12, 2012 at 5:21 AM, Girish K S >>>>> <girish.shivananjappa@xxxxxxxxxx> wrote: >>>>>> >>>>>> In the Current dwmmc driver there is support for selecting IDMAC from >>>>>> the menu config option. If the support for IDMAC is enabled in the menu >>>>>> config and Hardware configuration register's DMA_INTERFACE field is 0. >>>>>> Still the driver will try to do the DMA initialization. >>>>>> >>>>>> The dw_mci_idmac_init function currently implemented returns only success >>>>>> indicating that the DMA initialization is always successful. The current >>>>>> patch will add a ciheck for existance of the DMA IP and allow the >>>>>> DMA initialization. >>>>>> >>>>>> Signed-off-by: Girish K S <girish.shivananjappa@xxxxxxxxxx> >>>>>> --- >>>>>> drivers/mmc/host/dw_mmc.c | 11 ++++++++++- >>>>>> 1 files changed, 10 insertions(+), 1 deletions(-) >>>>> >>>>> This looks ok in principle. I'm wondering if we should only allow >>>>> dma_support == 0x01 (DW_DMA) in the IDMAC case? It's not clear from >>>>> the TRM what each of the DMA values means and I only have a system >>>>> with external DMA support at the moment. >>>> My understanding from the TRM >>>> if dma_support =1; then use designware dma ip for internal >>>> dma_support =2 then use any generic dma ip for internal dma tx >>>> this config is only for IDMA support. If there is a external DMA CTRL >>>> register should be used explicitly to enable DMA (there is no config >>>> available to tell external dma supported). correct me if i am wrong. >>> >>> That sounds like a reasonable interpretation of the TRM. ;-) >>> >>> Acked-by: Will Newton <will.newton@xxxxxxxxxx> >> I will resend the patch with minor change so that kernel doesnt crash >> but use PIO mode and continue even if IDMAC is enabled accidentally. >> what s your say? > > Yes, let's make sure it is robust against errors in configuration. i have tested the resent patch. scenario: 1. If IDMAC is enabled and if hardware actually doesnt have DMA controller. In that case it uses the PIO mode. provided the host->ring_size is initialized. thats the reson for moving the check below the ring_size initialize -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
