Re: [PATCH v2 2/5] mtd: nand: Qualcomm NAND controller driver

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On 7/30/2015 12:03 AM, Stephen Boyd wrote:
On 07/29, Archit Taneja wrote:
On 07/29/2015 07:18 AM, Stephen Boyd wrote:
On 07/27/2015 09:34 PM, Archit Taneja wrote:
Hi,

On 07/25/2015 06:21 AM, Stephen Boyd wrote:
On 07/21/2015 03:34 AM, Archit Taneja wrote:

+              int size)
+{Looks like a
+    struct desc_info *desc;
+    struct dma_async_tx_descriptor *dma_desc;
+    struct scatterlist *sgl;
+    int r;
+
+    desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+    if (!desc)
+        return -ENOMEM;
+
+    list_add_tail(&desc->list, &this->list);
+
+    sgl = &desc->sgl;
+
+    sg_init_one(sgl, vaddr, size);
+
+    desc->dir = DMA_MEM_TO_DEV;
+
+    r = dma_map_sg(this->dev, sgl, 1, desc->dir);
+    if (r == 0)
+        goto err;

Should we return an error in this case? Looks like return 0.

dma_map_sg returns the number of sg entries successfully mapped. In
this case, it should be 1.

Right, but this function returns 0 (success?) if we failed to map anything.

Yes. The return value is number of entries successfully mapped.
dma_map_sg is a macro that is replaced by dma_map_sg_attrs. Its
comment
says:

"dma_maps_sg_attrs returns 0 on error and > 0 on success. It should
never return a value < 0."

Yes, and so this function that calls dma_map_sg() is going to
return 0 to the caller when it didn't do what it was asked to do?

Ah, I get your point now :p. I thought you were referring to the
return value of dma_map_sg, and not write_data_dma. Will fix this.

Archit

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