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? -- 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
