Messages in this thread | | | Date | Wed, 29 May 2013 16:26:28 +0530 | From | Laxman Dewangan <> | Subject | Re: [PATCH 09/12] tegra20-apb-dma: remove useless use of lock |
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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.
But did not get why it is documented as locking is not require if shared variable is getting changed/access from different context simultaneously.
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