Hi Javi, On 9 December 2011 17:28, Javi Merino <javi.merino@xxxxxxx> wrote: > >>>>> Javi, could you please check if you too get the memcpy failure with >>>>> dmatest ? >>>> >> Ok, I think I've just reproduced it in my end with the kernel's dmatest >> module. After the first transaction it looks like the dma test wasn't >> able to issue any more transactions. I'll have a look at it tomorrow >> and try to answer my own questions ;) > > The problem is that pl330_submit_req() always puts the request in buffer 0 if > both buffers are free. > There should be nothing wrong in that. It is but natural to prefer 0 if both 0 and 1 are available. > If you submit a transaction, it finishes and there's nothing else to run, > pl330_update() calls _start() but there is nothing to send. This is all > right. Then, if another transaction is submitted, pl330_submit_req() will > put it in buffer 0 again. This time, the PC of the DMA is in the last > instruction of buffer 0 (the DMAEND of the *previous* transaction that > finished long ago) so _thrd_active() thinks that this buffer is active, > Many thanks for the in-depth analysis. Though before the PC check, the IS_FREE() should return true since pl330_update() does MARK_FREE() Could you please check if the client's callback function called successfully for the first submitted transfer ? Then we can decide upon one of the following 2 options (I *think* either should fix the issue) diff --git a/arch/arm/common/pl330.c b/arch/arm/common/pl330.c index 97912fa..f550d46 100644 --- a/arch/arm/common/pl330.c +++ b/arch/arm/common/pl330.c @@ -846,7 +846,7 @@ static inline bool _req_active(struct pl330_thread *thrd, if (IS_FREE(req)) return false; - return (pc >= buf && pc <= buf + req->mc_len) ? true : false; + return (pc >= buf && pc < buf + req->mc_len) ? true : false; } --OR-- diff --git a/arch/arm/common/pl330.c b/arch/arm/common/pl330.c index 97912fa..ad85a75 100644 --- a/arch/arm/common/pl330.c +++ b/arch/arm/common/pl330.c @@ -233,7 +233,7 @@ } while (0) /* If the _pl330_req is available to the client */ -#define IS_FREE(req) (*((u8 *)((req)->mc_cpu)) == CMD_DMAEND) +#define IS_FREE(req) ((req)->mc_len == 0) /* Use this _only_ to wait on transient states */ #define UNTIL(t, s) while (!(_state(t) & (s))) cpu_relax(); Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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