Date:   Wed, 12 Jul 2023 22:11:14 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     vireshk@...nel.org, nm@...com, sboyd@...nel.org,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        cw00.choi@...sung.com, andersson@...nel.org,
        konrad.dybcio@...aro.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        quic_asutoshd@...cinc.com, quic_cang@...cinc.com,
        quic_nitirawa@...cinc.com, quic_narepall@...cinc.com,
        quic_bhaskarv@...cinc.com, quic_richardp@...cinc.com,
        quic_nguyenb@...cinc.com, quic_ziqichen@...cinc.com,
        bmasney@...hat.com, krzysztof.kozlowski@...aro.org
Subject: Re: [PATCH 14/14] scsi: ufs: qcom: Add support for scaling
 interconnects

On Wed, Jul 12, 2023 at 04:22:51PM +0300, Dmitry Baryshkov wrote:
> On 12/07/2023 13:32, Manivannan Sadhasivam wrote:
> > Qcom SoCs require scaling the interconnect paths for proper working of the
> > peripherals connected through interconnects. Even for accessing the UFS
> > controller, someone should setup the interconnect paths. So far, the
> > bootloaders used to setup the interconnect paths before booting linux as
> > they need to access the UFS storage for things like fetching boot firmware.
> > But with the advent of multi boot options, bootloader nowadays like in
> > SA8540p SoC do not setup the interconnect paths at all.
> > 
> > So trying to configure UFS in the absence of the interconnect path
> > configuration, results in boot crash.
> > 
> > To fix this issue and also to dynamically scale the interconnects (UFS-DDR
> > and CPU-UFS), interconnect API support is added to the Qcom UFS driver.
> > With this support, the interconnect paths are scaled dynamically based on
> > the gear configuration.
> > 
> > During the early stage of ufs_qcom_init(), ufs_qcom_icc_init() will setup
> > the paths to max bandwidth to allow configuring the UFS registers. Touching
> > the registers without configuring the icc paths would result in a crash.
> > However, we don't really need to set max vote for the icc paths as any
> > minimal vote would suffice. But the max value would allow initialization to
> > be done faster. After init, the bandwidth will get updated using
> > ufs_qcom_icc_update_bw() based on the gear and lane configuration.
> > 
> > The bandwidth values defined in ufs_qcom_bw_table struct are taken from
> > Qcom downstream vendor devicetree source and are calculated as per the
> > UFS3.1 Spec, Section 6.4.1, HS Gear Rates. So it is fixed across platforms.
> > 
> > Cc: Brian Masney <bmasney@...hat.com>
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > ---
> >   drivers/ufs/host/ufs-qcom.c | 131 +++++++++++++++++++++++++++++++++++-
> >   drivers/ufs/host/ufs-qcom.h |   3 +
> >   2 files changed, 133 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> > index 8d6fd4c3324f..8a3132d45a65 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>
> > @@ -46,6 +47,49 @@ enum {
> >   	TSTBUS_MAX,
> >   };
> > +#define QCOM_UFS_MAX_GEAR 4
> > +#define QCOM_UFS_MAX_LANE 2
> > +
> > +enum {
> > +	MODE_MIN,
> > +	MODE_PWM,
> > +	MODE_HS_RA,
> > +	MODE_HS_RB,
> > +	MODE_MAX,
> 
> MODE_MIN and MODE_MAX seem to be unused
> 

No, they are used in the driver.

> > +};
> > +
> > +struct __ufs_qcom_bw_table {
> > +	u32 bw1;
> > +	u32 bw2;
> 
> Please consider:
> 
> s/bw1/mem_bw/
> s/bw2/cfg_bw/
> 

Ok.

> > +} ufs_qcom_bw_table[MODE_MAX + 1][QCOM_UFS_MAX_GEAR + 1][QCOM_UFS_MAX_LANE + 1] = {
> 
> I'd say, these +1's are slightly confusing and unnecessary.
> 

These max values itself are used in the table. Without adding 1 to them, we will
end up with out of bounds access.

> > +	[MODE_MIN][0][0] = { 0,		0 },	/* Bandwidth values are in KB/s */
> 
> I'd say, this becomes impossible to check. Can you please structure it?

What do you mean by "impossible to check"?

> Either by inclusion:
> 
> [MODE_PWM] = {
>   [1] = {
>      [1] = { .. },
>      [2] = { .. },
>   },
>   // etc.

Now, this seems confusion to me. The existing table looks fine IMO.

> };
> 
> Also, do we have defines for gears? Can we use them instead of indices?
> 

There are defines for the gears but not for lanes. So I ended up using numbers
for simplicity.

- Mani

> > +	[MODE_PWM][1][1] = { 922,	1000 },
> > +	[MODE_PWM][2][1] = { 1844,	1000 },
> > +	[MODE_PWM][3][1] = { 3688,	1000 },
> > +	[MODE_PWM][4][1] = { 7376,	1000 },
> > +	[MODE_PWM][1][2] = { 1844,	1000 },
> > +	[MODE_PWM][2][2] = { 3688,	1000 },
> > +	[MODE_PWM][3][2] = { 7376,	1000 },
> > +	[MODE_PWM][4][2] = { 14752,	1000 },
> > +	[MODE_HS_RA][1][1] = { 127796,	1000 },
> > +	[MODE_HS_RA][2][1] = { 255591,	1000 },
> > +	[MODE_HS_RA][3][1] = { 1492582,	102400 },
> > +	[MODE_HS_RA][4][1] = { 2915200,	204800 },
> > +	[MODE_HS_RA][1][2] = { 255591,	1000 },
> > +	[MODE_HS_RA][2][2] = { 511181,	1000 },
> > +	[MODE_HS_RA][3][2] = { 1492582,	204800 },
> > +	[MODE_HS_RA][4][2] = { 2915200,	409600 },
> > +	[MODE_HS_RB][1][1] = { 149422,	1000 },
> > +	[MODE_HS_RB][2][1] = { 298189,	1000 },
> > +	[MODE_HS_RB][3][1] = { 1492582,	102400 },
> > +	[MODE_HS_RB][4][1] = { 2915200,	204800 },
> > +	[MODE_HS_RB][1][2] = { 298189,	1000 },
> > +	[MODE_HS_RB][2][2] = { 596378,	1000 },
> > +	[MODE_HS_RB][3][2] = { 1492582,	204800 },
> > +	[MODE_HS_RB][4][2] = { 2915200,	409600 },
> > +	[MODE_MAX][0][0] = { 7643136, 307200 },
> > +};
> > +
> >   static struct ufs_qcom_host *ufs_qcom_hosts[MAX_UFS_QCOM_HOSTS];
> >   static void ufs_qcom_get_default_testbus_cfg(struct ufs_qcom_host *host);
> > @@ -789,6 +833,51 @@ static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, bool enable)
> >   	}
> >   }
> > +static int ufs_qcom_icc_set_bw(struct ufs_qcom_host *host, u32 bw1, u32 bw2)
> > +{
> > +	struct device *dev = host->hba->dev;
> > +	int ret;
> > +
> > +	ret = icc_set_bw(host->icc_ddr, 0, bw1);
> > +	if (ret < 0) {
> > +		dev_err(dev, "failed to set bandwidth request: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = icc_set_bw(host->icc_cpu, 0, bw2);
> > +	if (ret < 0) {
> > +		dev_err(dev, "failed to set bandwidth request: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static struct __ufs_qcom_bw_table ufs_qcom_get_bw_table(struct ufs_qcom_host *host)
> > +{
> > +	struct ufs_pa_layer_attr *p = &host->dev_req_params;
> > +	int gear = max_t(u32, p->gear_rx, p->gear_tx);
> > +	int lane = max_t(u32, p->lane_rx, p->lane_tx);
> > +
> > +	if (ufshcd_is_hs_mode(p)) {
> > +		if (p->hs_rate == PA_HS_MODE_B)
> > +			return ufs_qcom_bw_table[MODE_HS_RB][gear][lane];
> > +		else
> > +			return ufs_qcom_bw_table[MODE_HS_RA][gear][lane];
> > +	} else {
> > +		return ufs_qcom_bw_table[MODE_PWM][gear][lane];
> > +	}
> > +}
> > +
> > +static int ufs_qcom_icc_update_bw(struct ufs_qcom_host *host)
> > +{
> > +	struct __ufs_qcom_bw_table bw_table;
> > +
> > +	bw_table = ufs_qcom_get_bw_table(host);
> > +
> > +	return ufs_qcom_icc_set_bw(host, bw_table.bw1, bw_table.bw2);
> > +}
> > +
> >   static int ufs_qcom_pwr_change_notify(struct ufs_hba *hba,
> >   				enum ufs_notify_change_status status,
> >   				struct ufs_pa_layer_attr *dev_max_params,
> > @@ -852,6 +941,8 @@ static int ufs_qcom_pwr_change_notify(struct ufs_hba *hba,
> >   		memcpy(&host->dev_req_params,
> >   				dev_req_params, sizeof(*dev_req_params));
> > +		ufs_qcom_icc_update_bw(host);
> > +
> >   		/* disable the device ref clock if entered PWM mode */
> >   		if (ufshcd_is_hs_mode(&hba->pwr_info) &&
> >   			!ufshcd_is_hs_mode(dev_req_params))
> > @@ -981,7 +1072,9 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
> >   	switch (status) {
> >   	case PRE_CHANGE:
> > -		if (!on) {
> > +		if (on) {
> > +			ufs_qcom_icc_update_bw(host);
> > +		} else {
> >   			if (!ufs_qcom_is_link_active(hba)) {
> >   				/* disable device ref_clk */
> >   				ufs_qcom_dev_ref_clk_ctrl(host, false);
> > @@ -993,6 +1086,9 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
> >   			/* enable the device ref clock for HS mode*/
> >   			if (ufshcd_is_hs_mode(&hba->pwr_info))
> >   				ufs_qcom_dev_ref_clk_ctrl(host, true);
> > +		} else {
> > +			ufs_qcom_icc_set_bw(host, ufs_qcom_bw_table[MODE_MIN][0][0].bw1,
> > +					    ufs_qcom_bw_table[MODE_MIN][0][0].bw2);
> >   		}
> >   		break;
> >   	}
> > @@ -1031,6 +1127,34 @@ static const struct reset_control_ops ufs_qcom_reset_ops = {
> >   	.deassert = ufs_qcom_reset_deassert,
> >   };
> > +static int ufs_qcom_icc_init(struct ufs_qcom_host *host)
> > +{
> > +	struct device *dev = host->hba->dev;
> > +	int ret;
> > +
> > +	host->icc_ddr = devm_of_icc_get(dev, "ufs-ddr");
> > +	if (IS_ERR(host->icc_ddr))
> > +		return dev_err_probe(dev, PTR_ERR(host->icc_ddr),
> > +				    "failed to acquire interconnect path\n");
> > +
> > +	host->icc_cpu = devm_of_icc_get(dev, "cpu-ufs");
> > +	if (IS_ERR(host->icc_cpu))
> > +		return dev_err_probe(dev, PTR_ERR(host->icc_cpu),
> > +				    "failed to acquire interconnect path\n");
> > +
> > +	/*
> > +	 * Set Maximum bandwidth vote before initializing the UFS controller and
> > +	 * device. Ideally, a minimal interconnect vote would suffice for the
> > +	 * initialization, but a max vote would allow faster initialization.
> > +	 */
> > +	ret = ufs_qcom_icc_set_bw(host, ufs_qcom_bw_table[MODE_MAX][0][0].bw1,
> > +				  ufs_qcom_bw_table[MODE_MAX][0][0].bw2);
> > +	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
> > @@ -1085,6 +1209,10 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> >   		}
> >   	}
> > +	err = ufs_qcom_icc_init(host);
> > +	if (err)
> > +		goto out_variant_clear;
> > +
> >   	host->device_reset = devm_gpiod_get_optional(dev, "reset",
> >   						     GPIOD_OUT_HIGH);
> >   	if (IS_ERR(host->device_reset)) {
> > @@ -1282,6 +1410,7 @@ static int ufs_qcom_clk_scale_notify(struct ufs_hba *hba,
> >   				    dev_req_params->pwr_rx,
> >   				    dev_req_params->hs_rate,
> >   				    false);
> > +		ufs_qcom_icc_update_bw(host);
> >   		ufshcd_uic_hibern8_exit(hba);
> >   	}
> > diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
> > index 6289ad5a42d0..dc27395ecba1 100644
> > --- a/drivers/ufs/host/ufs-qcom.h
> > +++ b/drivers/ufs/host/ufs-qcom.h
> > @@ -206,6 +206,9 @@ struct ufs_qcom_host {
> >   	struct clk *tx_l1_sync_clk;
> >   	bool is_lane_clks_enabled;
> > +	struct icc_path *icc_ddr;
> > +	struct icc_path *icc_cpu;
> > +
> >   #ifdef CONFIG_SCSI_UFS_CRYPTO
> >   	struct qcom_ice *ice;
> >   #endif
> 
> -- 
> With best wishes
> Dmitry
> 

-- 
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