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SubjectRe: [PATCH 2/2] usb; dwc3: of-simple: Add support to get resets for the device
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Date
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@kernel.org>
>> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
>> ---
>>
>> 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
>

--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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