linux-kernel - Re: [PATCH v5 09/10] phy: qualcomm: phy-qcom-qmp-ufs: Add High Speed Gear 5 support for SM8550

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Date:   Tue, 28 Nov 2023 12:17:21 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Can Guo <quic_cang@...cinc.com>
Cc:     bvanassche@....org, adrian.hunter@...el.com, beanhuo@...ron.com,
        avri.altman@....com, junwoo80.lee@...sung.com,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        "open list:GENERIC PHY FRAMEWORK" <linux-phy@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 09/10] phy: qualcomm: phy-qcom-qmp-ufs: Add High Speed
 Gear 5 support for SM8550

On Thu, Nov 23, 2023 at 12:46:29AM -0800, Can Guo wrote:
> On SM8550, two sets of UFS PHY settings are provided, one set is to support
> HS-G5, another set is to support HS-G4 and lower gears. The two sets of PHY
> settings are programming different values to different registers, mixing
> the two sets and/or overwriting one set with another set is definitely not
> blessed by UFS PHY designers.
> 
> To add HS-G5 support for SM8550, split the two sets of PHY settings into
> their dedicated overlay tables, only the common parts of the two sets of
> PHY settings are left in the .tbls.
> 
> Consider we are going to add even higher gear support in future, to avoid
> adding more tables with different names, rename the .tbls_hs_g4 and make it
> an array, a size of 2 is enough as of now.
> 
> In this case, .tbls alone is not a complete set of PHY settings, so either
> tbls_hs_overlay[0] or tbls_hs_overlay[1] must be applied on top of the
> .tbls to become a complete set of PHY settings.
> 

Thanks for the update! This really helps in minimizing the changes for future
gears.

> Signed-off-by: Can Guo <quic_cang@...cinc.com>
> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-pcs-ufs-v6.h     |   2 +
>  drivers/phy/qualcomm/phy-qcom-qmp-qserdes-com-v6.h |   2 +
>  .../qualcomm/phy-qcom-qmp-qserdes-txrx-ufs-v6.h    |   9 ++
>  drivers/phy/qualcomm/phy-qcom-qmp-ufs.c            | 174 ++++++++++++++++++---
>  4 files changed, 166 insertions(+), 21 deletions(-)
> 
>  

[...]

> -static void qmp_ufs_init_registers(struct qmp_ufs *qmp, const struct qmp_phy_cfg *cfg)
> +static bool qmp_ufs_match_gear_overlay(struct qmp_ufs *qmp, const struct qmp_phy_cfg *cfg, int *i)
> +{
> +	u32 max_gear, floor_max_gear = cfg->max_supported_gear;
> +	bool found = false;
> +	int j;
> +
> +	for (j = 0; j < NUM_OVERLAY; j ++) {
> +		max_gear = cfg->tbls_hs_overlay[j].max_gear;
> +
> +		if (max_gear == 0)

Is this condition possible for hs_overlay tables?

> +			continue;
> +
> +		/* Direct matching, bail */
> +		if (qmp->submode == max_gear) {
> +			*i = j;
> +			return true;
> +		}
> +
> +		/* If no direct matching, the lowest gear is the best matching */
> +		if (max_gear < floor_max_gear) {

Can you start the loop from max? If looks odd to set the matching params in the
first iteration itself and then checking the next one.

> +			*i = j;
> +			found = true;
> +			floor_max_gear = max_gear;
> +		}
> +	}
> +
> +	return found;
> +}
> +
> +static int qmp_ufs_init_registers(struct qmp_ufs *qmp, const struct qmp_phy_cfg *cfg)
>  {
> +	bool apply_overlay;
> +	int i;
> +
> +	if (qmp->submode > cfg->max_supported_gear || qmp->submode == 0) {
> +		dev_err(qmp->dev, "Invalid PHY submode %u\n", qmp->submode);
> +		return -EINVAL;
> +	}

This check should be moved to qmp_ufs_set_mode().

Rest LGTM.

- Mani

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