Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

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On 12/19/2015 1:05 PM, Måns Rullgård wrote:
Andy Shevchenko <andy.shevchenko@xxxxxxxxx> writes:

On Sat, Dec 19, 2015 at 5:40 PM, Måns Rullgård <mans@xxxxxxxxx> wrote:

OK, I've found something.  The dma setup errors are benign, caused by
the driver calling dmaengine_prep_slave_sg() even for non-dma
operations.
I suppose the following is a quick fix to avoid preparing descriptor
for non-DMA operations (not tested anyhow)

a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
@@ -1041,6 +1041,9 @@ static void sata_dwc_qc_prep_by_tag(struct
ata_queued_cmd *qc, u8 tag)
                 __func__, ap->port_no, get_dma_dir_descript(qc->dma_dir),
                  qc->n_elem);

+       if (!is_slave_direction(qc->dma_dir))
+               return;
+
         desc = dma_dwc_xfer_setup(qc);
         if (!desc) {
                 dev_err(ap->dev, "%s: dma_dwc_xfer_setup returns NULL\n",
I already have a better patch sitting here.

The real error is the lock recursion that's reported
later.  I wasn't seeing it since I was running a UP non-preempt kernel.
With lock debugging enabled, I get the same error.  This patch should
fix it.
-       spin_lock_irqsave(&ap->host->lock, flags);
         hsdevp->cmd_issued[tag] = cmd_issued;
-       spin_unlock_irqrestore(&ap->host->lock, flags);
+
This will create a second empty line, though I don't care it is so minor.
The patch leaves one blank line before the following block comment.  I
think it looks better that way.


Still can't get the patch applied .

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