linux-kernel - Re: [PATCH v3 2/7] reset: qcom: AOSS (always on subsystem) reset controller

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Message-ID: <386f26c8-2d7f-2066-758f-7bf1498cdaa6@codeaurora.org>
Date:   Fri, 23 Mar 2018 04:02:53 +0530
From:   Sibi S <sibis@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     p.zabel@...gutronix.de, robh+dt@...nel.org,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, georgi.djakov@...aro.org,
        jassisinghbrar@...il.com, ohad@...ery.com, mark.rutland@....com,
        kyan@...eaurora.org, sricharan@...eaurora.org,
        akdwived@...eaurora.org, linux-arm-msm@...r.kernel.org,
        tsoni@...eaurora.org
Subject: Re: [PATCH v3 2/7] reset: qcom: AOSS (always on subsystem) reset
 controller

Hi Bjorn,
Thanks for the review.

On 03/19/2018 04:15 AM, Bjorn Andersson wrote:
> On Wed 14 Mar 02:21 PDT 2018, Sibi S wrote:
>> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
>> index 7fc7769..d06bd1d 100644
>> --- a/drivers/reset/Kconfig
>> +++ b/drivers/reset/Kconfig
>> @@ -81,6 +81,16 @@ config RESET_PISTACHIO
>>   	help
>>   	  This enables the reset driver for ImgTec Pistachio SoCs.
>>   
>> +config RESET_QCOM_AOSS
>> +	bool "Qcom AOSS Reset Driver"
>> +	depends on ARCH_QCOM || COMPILE_TEST
>> +	select MFD_SYSCON
> 
> Drop syscon
> 

will drop it

>> +	help
>> +	  This enables the AOSS (always on subsystem) reset driver
>> +	  for Qualcomm SDM845 SoCs. Say Y if you want to control
>> +	  reset signals provided by AOSS for Modem, Venus, ADSP,
>> +	  GPU, Camera, Wireless, Display subsystem. Otherwise, say N.
>> +
> [..]
>> diff --git a/drivers/reset/reset-qcom-aoss.c b/drivers/reset/reset-qcom-aoss.c
> [..]
>> +static const struct regmap_config sdm845_aoss_regmap_config = {
>> +	.name		= "aoss-reset",
>> +	.reg_bits	= 32,
>> +	.reg_stride	= 4,
>> +	.val_bits	= 32,
>> +	.max_register	= 0x20000,
>> +	.fast_io	= true,
>> +};
> 
> Is there a particular reason why you're setting up a regmap and not just
> operate on the ioremap region directly with readl/writel? It would save
> you a few lines of code and some runtime memory.
> 

The idea here is to reuse the driver in modified configuration as
pdc_sync restart controller which is to be used for adsp_pil. PDC sync
reset register is a single register with multiple reset lines hence
would warrant setting up a regmap. I can remove these changes and add
them when I add pdc_sync reset controller though.

>> +
>> +static const struct qcom_aoss_reset_map sdm845_aoss_resets[] = {
>> +	[AOSS_CC_MSS_RESTART] = { 0x0, 0 },
>> +	[AOSS_CC_CAMSS_RESTART] = { 0x1000, 0 },
>> +	[AOSS_CC_VENUS_RESTART] = { 0x2000, 0 },
>> +	[AOSS_CC_GPU_RESTART] = { 0x3000, 0 },
>> +	[AOSS_CC_DISPSS_RESTART] = { 0x4000, 0 },
>> +	[AOSS_CC_WCSS_RESTART] = { 0x10000, 0 },
>> +	[AOSS_CC_LPASS_RESTART] = { 0x20000, 0 },
> 
> Do you have a case where bit != 0? If not please drop the bit until it's
> necessary.
> 

had the bit variable for the above state reason.

>> +};
>> +
>> +static const struct qcom_aoss_desc sdm845_aoss_desc = {
>> +	.config = &sdm845_aoss_regmap_config,
>> +	.resets = sdm845_aoss_resets,
>> +	/* Wait 6 32kHz sleep cycles for reset */
>> +	.delay = 200,
> 
> Please move this constant into qcom_aoss_control_reset(), until there's
> a need for it to be configurable.
> 
>> +	.num_resets = ARRAY_SIZE(sdm845_aoss_resets),
>> +};
>> +
> [..]
>> +static int qcom_aoss_control_reset(struct reset_controller_dev *rcdev,
>> +					unsigned long idx)
>> +{
>> +	struct qcom_aoss_reset_data *data = to_qcom_aoss_reset_data(rcdev);
>> +	int ret;
>> +
>> +	ret = qcom_aoss_control_assert(rcdev, idx);
>> +	if (ret)
>> +		return ret;
>> +
>> +	udelay(data->desc->delay);
> 
> Per Documentation/timers/timers-howto.txt please use usleep_range() when
> delays are between 10us and 20ms.
> 

will replace them

>> +
>> +	return qcom_aoss_control_deassert(rcdev, idx);
>> +}
> 
> Regards,
> Bjorn
> 

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