Re: spi: rockchip: check requesting dma channel with EPROBE_DEFER

[Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>]

On 2016/3/14 17:48, Dan Carpenter wrote:
> Hello Shawn Lin,
>
> The patch 61cadcf46cfd: "spi: rockchip: check requesting dma channel
> with EPROBE_DEFER" from Mar 9, 2016, leads to the following static
> checker warning:
>
> 	drivers/spi/spi-rockchip.c:742 rockchip_spi_probe()
> 	warn: passing zero to 'PTR_ERR'
>
> drivers/spi/spi-rockchip.c
>     732
>     733          rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx");
>     734          if (IS_ERR_OR_NULL(rs->dma_tx.ch)) {
>     735                  /* Check tx to see if we need defer probing driver */
>     736                  if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) {
>     737                          ret = -EPROBE_DEFER;
>     738                          goto err_get_fifo_len;
>
> What's going on here?  Are we planning to change dma_request_slave_channel()
> to return error pointers?  Also what about other error pointers besides
> EPROBE_DEFER it seems dangerous to leave rs->dma_tx.ch as an error
> pointer.  We probably eventually try to free it if it's non-NULL.

yes, we are plannig to return EPROBE_DEFER/NULL for
dma_request_slave_channel to make sure we don't decide
the dma cap based on driver probe sequence.

No any other error pointer will be returned to the caller

>
>     739                  }
>     740                  dev_warn(rs->dev, "Failed to request TX DMA channel\n");
>     741          }
>     742
>
> regards,
> dan carpenter
>
>
>


-- 
Best Regards
Shawn Lin

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