Re: [PATCH 2/2] xilinx_dma: Add reset support

From: Ramiro Oliveira
Date: Thu Dec 15 2016 - 06:27:40 EST


Hi Laurent,

Thank you for your feedback.

On 12/14/2016 8:16 PM, Laurent Pinchart wrote:
> Hi Ramiro,
>
> Thank you for the patch.
>
> On Wednesday 14 Dec 2016 17:18:24 Ramiro Oliveira wrote:
>> Add a DT property to control an optional external reset line
>>
>> Signed-off-by: Ramiro Oliveira <roliveir@xxxxxxxxxxxx>
>> ---
>> drivers/dma/xilinx/xilinx_dma.c | 23 +++++++++++++++++++++++
>> 1 file changed, 23 insertions(+)
>>
>> diff --git a/drivers/dma/xilinx/xilinx_dma.c
>> b/drivers/dma/xilinx/xilinx_dma.c index 5c9f11b..b845224 100644
>> --- a/drivers/dma/xilinx/xilinx_dma.c
>> +++ b/drivers/dma/xilinx/xilinx_dma.c
>> @@ -46,6 +46,7 @@
>> #include <linux/slab.h>
>> #include <linux/clk.h>
>> #include <linux/io-64-nonatomic-lo-hi.h>
>> +#include <linux/reset.h>
>
> I had neatly sorted the header alphabetically until someone added clk.h and
> io-64-nonatomic-lo-hi.h :-( Could you please move reset.h just before slab.h ?
>

Sure. Actually I was tempted to reorder it, but I decided not to do it. I'll do
it now

>>
>> #include "../dmaengine.h"
>>
>> @@ -409,6 +410,7 @@ struct xilinx_dma_device {
>> struct clk *rxs_clk;
>> u32 nr_channels;
>> u32 chan_id;
>> + struct reset_control *rst;
>> };
>>
>> /* Macros */
>> @@ -2543,6 +2545,27 @@ static int xilinx_dma_probe(struct platform_device
>> *pdev) if (IS_ERR(xdev->regs))
>> return PTR_ERR(xdev->regs);
>>
>> + xdev->rst = devm_reset_control_get_optional(&pdev->dev, "reset");
>
> devm_reset_control_get_optional() is deprecated as explained in linux/reset.h,
> you should use devm_reset_control_get_optional_exclusive() or
> devm_reset_control_get_optional_shared() instead, as applicable.
>
> This being said, I'm wondering why the optional versions of those functions
> exist, as they do exactly the same as the non-optional versions. The API feels
> wrong, it should have been modelled like the GPIO API. Feel free to fix it if
> you want :-) But that's out of scope for this patch.
>

I missed the comment stating that devm_reset_control_get_optional() was deprecated.

I could fix it. Your sugestion is modelling these functions like the GPIO API?

>> + if (IS_ERR(xdev->rst)) {
>> + err = PTR_ERR(xdev->rst);
>> + switch (err) {
>> + case -ENOENT:
>
> If you drop the name as proposed in the review of patch 1/2 you don't have to
> check for -ENOENT.
>

I'll do that.

>> + case -ENOTSUPP:
>> + xdev->rst = NULL;
>> + break;
>
> Wrong indentation.
>
> You need to handle -EPROBE_DEFER and defer probing of the xilinx_dma device.
>
>> + default:
>> + dev_err(xdev->dev, "error getting reset %d\n", err);
>> + return err;
>
> Wrong indentation.
>
>> + }
>> + } else {
>> + err = reset_control_deassert(xdev->rst);
>> + if (err) {
>> + dev_err(xdev->dev, "failed to deassert reset: %d\n",
>> + err);
>
> Wrong indentation.
>
>> + return err;
>> + }
>> + }
>> +
>> /* Retrieve the DMA engine properties from the device tree */
>> xdev->has_sg = of_property_read_bool(node, "xlnx,include-sg");
>> if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA)
>