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

From: Bjorn Andersson
Date: Sun Mar 18 2018 - 18:45:21 EST


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

> + 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.

> +
> +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.

> +};
> +
> +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.

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

Regards,
Bjorn