Commit 9ec54934 authored by Avri Altman's avatar Avri Altman Committed by Martin K. Petersen
Browse files

scsi: ufs: core: Allow RTT negotiation 



The rtt-upiu packets precede any data-out upiu packets, thus synchronizing
the data input to the device: this mostly applies to write operations, but
there are other operations that requires rtt as well.

There are several rules binding this rtt - data-out dialog, specifically
There can be at most outstanding bMaxNumOfRTT such packets.  This might
have an effect on write performance (sequential write in particular), as
each data-out upiu must wait for its rtt sibling.

UFSHCI expects bMaxNumOfRTT to be min(bDeviceRTTCap, NORTT). However, as of
today, there does not appears to be no-one who sets it: not the host
controller nor the driver.  It wasn't an issue up to now: bMaxNumOfRTT is
set to 2 after manufacturing, and wasn't limiting the write performance.

UFS4.0, and specifically gear 5 changes this, and requires the device to be
more attentive.  This doesn't come free - the device has to allocate more
resources to that end, but the sequential write performance improvement is
significant. Early measurements shows 25% gain when moving from rtt 2 to
9. Therefore, set bMaxNumOfRTT to be min(bDeviceRTTCap, NORTT) as UFSHCI
expects.

Signed-off-by: default avatarAvri Altman <avri.altman@wdc.com>
Link: https://lore.kernel.org/r/20240530142510.734-2-avri.altman@wdc.com


Reviewed-by: default avatarBean Huo <beanhuo@micron.com>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 1613e604

drivers/ufs/core/ufshcd.c

+38 −0
Original line number Diff line number Diff line
@@ -102,6 +102,9 @@ 
/* Default RTC update every 10 seconds */

#define UFS_RTC_UPDATE_INTERVAL_MS (10 * MSEC_PER_SEC)



/* bMaxNumOfRTT is equal to two after device manufacturing */

#define DEFAULT_MAX_NUM_RTT 2



/* UFSHC 4.0 compliant HC support this mode. */

static bool use_mcq_mode = true;
@@ -2405,6 +2408,8 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba) 
	((hba->capabilities & MASK_TASK_MANAGEMENT_REQUEST_SLOTS) >> 16) + 1;

	hba->reserved_slot = hba->nutrs - 1;



	hba->nortt = FIELD_GET(MASK_NUMBER_OUTSTANDING_RTT, hba->capabilities) + 1;



	/* Read crypto capabilities */

	err = ufshcd_hba_init_crypto_capabilities(hba);

	if (err) {
@@ -8121,6 +8126,35 @@ static void ufshcd_ext_iid_probe(struct ufs_hba *hba, u8 *desc_buf) 
	dev_info->b_ext_iid_en = ext_iid_en;

}



static void ufshcd_set_rtt(struct ufs_hba *hba)

{

	struct ufs_dev_info *dev_info = &hba->dev_info;

	u32 rtt = 0;

	u32 dev_rtt = 0;



	/* RTT override makes sense only for UFS-4.0 and above */

	if (dev_info->wspecversion < 0x400)

		return;



	if (ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,

				    QUERY_ATTR_IDN_MAX_NUM_OF_RTT, 0, 0, &dev_rtt)) {

		dev_err(hba->dev, "failed reading bMaxNumOfRTT\n");

		return;

	}



	/* do not override if it was already written */

	if (dev_rtt != DEFAULT_MAX_NUM_RTT)

		return;



	rtt = min_t(int, dev_info->rtt_cap, hba->nortt);

	if (rtt == dev_rtt)

		return;



	if (ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,

				    QUERY_ATTR_IDN_MAX_NUM_OF_RTT, 0, 0, &rtt))

		dev_err(hba->dev, "failed writing bMaxNumOfRTT\n");

}



void ufshcd_fixup_dev_quirks(struct ufs_hba *hba,

			     const struct ufs_dev_quirk *fixups)

{
@@ -8256,6 +8290,8 @@ static int ufs_get_device_desc(struct ufs_hba *hba) 
				      desc_buf[DEVICE_DESC_PARAM_SPEC_VER + 1];

	dev_info->bqueuedepth = desc_buf[DEVICE_DESC_PARAM_Q_DPTH];



	dev_info->rtt_cap = desc_buf[DEVICE_DESC_PARAM_RTT_CAP];



	model_index = desc_buf[DEVICE_DESC_PARAM_PRDCT_NAME];



	err = ufshcd_read_string_desc(hba, model_index,
@@ -8508,6 +8544,8 @@ static int ufshcd_device_params_init(struct ufs_hba *hba) 
		goto out;

	}



	ufshcd_set_rtt(hba);



	ufshcd_get_ref_clk_gating_wait(hba);



	if (!ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_READ_FLAG,

include/ufs/ufs.h

+2 −0
Original line number Diff line number Diff line
@@ -592,6 +592,8 @@ struct ufs_dev_info { 
	enum ufs_rtc_time rtc_type;

	time64_t rtc_time_baseline;

	u32 rtc_update_period;



	u8 rtt_cap; /* bDeviceRTTCap */

};



/*

include/ufs/ufshcd.h

+2 −0
Original line number Diff line number Diff line
@@ -819,6 +819,7 @@ enum ufshcd_mcq_opr { 
 * @capabilities: UFS Controller Capabilities

 * @mcq_capabilities: UFS Multi Circular Queue capabilities

 * @nutrs: Transfer Request Queue depth supported by controller

 * @nortt - Max outstanding RTTs supported by controller

 * @nutmrs: Task Management Queue depth supported by controller

 * @reserved_slot: Used to submit device commands. Protected by @dev_cmd.lock.

 * @ufs_version: UFS Version to which controller complies
@@ -957,6 +958,7 @@ struct ufs_hba { 


	u32 capabilities;

	int nutrs;

	int nortt;

	u32 mcq_capabilities;

	int nutmrs;

	u32 reserved_slot;

include/ufs/ufshci.h

+1 −0
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ enum { 
/* Controller capability masks */

enum {

	MASK_TRANSFER_REQUESTS_SLOTS		= 0x0000001F,

	MASK_NUMBER_OUTSTANDING_RTT		= 0x0000FF00,

	MASK_TASK_MANAGEMENT_REQUEST_SLOTS	= 0x00070000,

	MASK_EHSLUTRD_SUPPORTED			= 0x00400000,

	MASK_AUTO_HIBERN8_SUPPORT		= 0x00800000,