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scsi: ufs: core: Allow RTT negotiation

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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: Avri Altman <avri.altman@wdc.com>
Link: https://lore.kernel.org/r/20240530142510.734-2-avri.altman@wdc.com
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Avri Altman 2024-05-30 17:25:07 +03:00 committed by Martin K. Petersen
parent 1613e604df
commit 9ec54934ce
4 changed files with 43 additions and 0 deletions
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38
drivers/ufs/core/ufshcd.c
View file

@ -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,

2
include/ufs/ufs.h
View file

@ -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 */
};
/*

2
include/ufs/ufshcd.h
View file

@ -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;

1
include/ufs/ufshci.h
View file

@ -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,