linux-kernel - Re: [PATCH 1/2] scsi: ufs: ufs-qcom: add basic interconnect support

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Message-ID: <20221117113357.GB93179@thinkpad>
Date:   Thu, 17 Nov 2022 17:03:57 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Brian Masney <bmasney@...hat.com>
Cc:     andersson@...nel.org, agross@...nel.org, konrad.dybcio@...aro.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        jejb@...ux.ibm.com, martin.petersen@...cle.com,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH 1/2] scsi: ufs: ufs-qcom: add basic interconnect support

On Thu, Nov 17, 2022 at 05:49:56AM -0500, Brian Masney wrote:
> The firmware on the Qualcomm platforms expects the interconnect votes to
> be present. Let's add very basic support where the maximum throughput is
> requested to match what's done in a few other drivers.
> 
> This will not break boot on systems where the interconnects and
> interconnect-names properties are not specified in device tree for UFS
> since the interconnect framework will silently return.
> 
> Signed-off-by: Brian Masney <bmasney@...hat.com>
> ---
>  drivers/ufs/host/ufs-qcom.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index 8ad1415e10b6..55bf8dd88985 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -7,6 +7,7 @@
>  #include <linux/time.h>
>  #include <linux/clk.h>
>  #include <linux/delay.h>
> +#include <linux/interconnect.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
> @@ -936,6 +937,22 @@ static const struct reset_control_ops ufs_qcom_reset_ops = {
>  	.deassert = ufs_qcom_reset_deassert,
>  };
>  
> +static int ufs_qcom_icc_init(struct device *dev, char *pathname)
> +{
> +	struct icc_path *path;
> +	int ret;
> +
> +	path = devm_of_icc_get(dev, pathname);
> +	if (IS_ERR(path))
> +		return dev_err_probe(dev, PTR_ERR(path), "failed to acquire interconnect path\n");
> +
> +	ret = icc_set_bw(path, 0, UINT_MAX);

Please use icc macros for setting the bandwidth. Like, GBps_to_icc(),
MBps_to_icc() etc...

Also, during the init stage you can set a minimum bandwidth that will allow the
controller to get probed successfully. Then, you should update the bandwidth
based on the gear in pwr_change_notify() callback.

> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "failed to set bandwidth request\n");
> +
> +	return 0;
> +}
> +
>  /**
>   * ufs_qcom_init - bind phy with controller
>   * @hba: host controller instance
> @@ -991,6 +1008,14 @@ static int ufs_qcom_init(struct ufs_hba *hba)
>  			err = dev_err_probe(dev, PTR_ERR(host->generic_phy), "Failed to get PHY\n");
>  			goto out_variant_clear;
>  		}
> +
> +		err = ufs_qcom_icc_init(dev, "ufs-ddr");
> +		if (err)
> +			goto out_variant_clear;
> +
> +		err = ufs_qcom_icc_init(dev, "cpu-ufs");
> +		if (err)
> +			goto out_variant_clear;

It'd be nice to have a single function that initializes both paths.

Thanks,
Mani

>  	}
>  
>  	host->device_reset = devm_gpiod_get_optional(dev, "reset",
> -- 
> 2.38.1
> 

-- 
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