Re: [PATCH 2/2] usb; dwc3: of-simple: Add support to get resets for the device

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Hi,


On 03/15/2017 04:15 PM, Philipp Zabel wrote:
On Wed, 2017-02-22 at 10:54 +0530, Vivek Gautam wrote:
Add support to get a list of resets available for the device.
These resets must be kept de-asserted until the device is
in use.

Cc: Felipe Balbi <balbi@xxxxxxxxxx>
Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
---

Based on torvald's master branch.

  drivers/usb/dwc3/dwc3-of-simple.c | 49 +++++++++++++++++++++++++++++++++++++++
  1 file changed, 49 insertions(+)

diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c
index fe414e7a9c78..025de7342d28 100644
--- a/drivers/usb/dwc3/dwc3-of-simple.c
+++ b/drivers/usb/dwc3/dwc3-of-simple.c
@@ -29,13 +29,52 @@
  #include <linux/of.h>
  #include <linux/of_platform.h>
  #include <linux/pm_runtime.h>
+#include <linux/reset.h>
struct dwc3_of_simple {
  	struct device		*dev;
  	struct clk		**clks;
  	int			num_clocks;
+	struct reset_control	**resets;
+	int			num_resets;
  };
+static int dwc3_of_simple_reset_init(struct dwc3_of_simple *simple, int count)
+{
+	struct device		*dev = simple->dev;
+	int			i;
+
+	simple->num_resets = count;
+
+	if (!count)
+		return 0;
+
+	simple->resets = devm_kcalloc(dev, simple->num_resets,
+				sizeof(struct reset_control *), GFP_KERNEL);
+	if (!simple->resets)
+		return -ENOMEM;
+
+	for (i = 0; i < simple->num_resets; i++) {
+		struct reset_control *reset;
+		int ret;
+
+		reset = devm_reset_control_get_by_index(dev, i);
Please use devm_reset_control_get_exclusive_by_index instead. See
include/linux/reset.h for details.

Sure, will make use of *exclusive version of the api.


+		if (IS_ERR(reset))
+			return PTR_ERR(reset);
+
+		simple->resets[i] = reset;
+
+		ret = reset_control_deassert(reset);
+		if (ret) {
+			while (--i >= 0)
+				reset_control_assert(reset);
+			return ret;
+		}
+	}
+
+	return 0;
+}
This looks rather generic. Should we have a
reset_control_get/assert/deassert_array functionality at the reset API
level?

Yes, i think we should. Something on the lines of 'regulator_bulk_*' interface?


  static int dwc3_of_simple_clk_init(struct dwc3_of_simple *simple, int count)
  {
  	struct device		*dev = simple->dev;
@@ -100,6 +139,10 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
  	if (ret)
  		return ret;
+ ret = dwc3_of_simple_reset_init(simple, of_reset_control_get_count(np));
+	if (ret)
+		return ret;
+
Not a blocker, but it seems a bit inconsistent to count the reset
controls via the device node (of_...), but then get them via the device
(devm_reset_control_get_... instead of of_reset_control_get_...).

You are right, it looks inconsistent. I thought of using a resource
managed API. But now i think it doesn't make much sense.


Best Regards
Vivek


regards
Philipp


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