On Wed, May 29, 2013 at 1:56 PM, Laxman Dewangan <ldewangan@xxxxxxxxxx> wrote: > On Monday 27 May 2013 05:44 PM, Andy Shevchenko wrote: >> >> Accordingly to dma_cookie_status() description locking is not required. >> > I think we need lock here: > From isr handler, we call dma_cookie_complete() which is in spin-locked. > This function updates tx->chan->completed_cookie = tx->cookie; > In tegra_dma_tx_status(), we check for dma_cookie_status() which access the > chan->completed_cookie; and it decides status based on this > > As the access of chan->completed_cookie are from different context, we > need this locking. You need to have a consistent data in the cookies. This is guaranteed by memory barrier if I got it correctly. -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
