Re: [PATCH v9 09/27] dmaengine: dw-edma: Drop chancnt initialization

[Bjorn Helgaas]

On Fri, Jan 13, 2023 at 08:13:51PM +0300, Serge Semin wrote:
> DMA device drivers aren't supposed to initialize the dma_device.chancnt
> field. It will be done by the DMA-engine core in accordance with number of
> added virtual DMA-channels. Pre-initializing it with some value causes
> having a wrong number of channels printed in the device summary.
> 
> Fixes: e63d79d1ffcd ("dmaengine: Add Synopsys eDMA IP core driver")
> Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Acked-by: Vinod Koul <vkoul@xxxxxxxxxx>
> ---
>  drivers/dma/dw-edma/dw-edma-core.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index 6c9f95a8e397..ecd3e8f7ac5d 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -817,7 +817,6 @@ static int dw_edma_channel_setup(struct dw_edma *dw, bool write,
>  	dma->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
>  	dma->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
>  	dma->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
> -	dma->chancnt = cnt;

Did you look for other instances of this bug?  There are several other
places that *look* like they might have the same issue:

  axi_dmac_probe
  dw_probe               (dw-axi-dmac-platform.c)
  ioat_pci_probe
  plx_dma_create
  ...

I hate to fix just one if there are other similar issues.

>  	/* Set DMA channel callbacks */
>  	dma->dev = chip->dev;
> -- 
> 2.39.0
> 
>