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 <[email protected]>
---
Changes since v1:
- bMaxNumOfRTT is a Persistent attribute - do not override if it was
written (Bean)
---
drivers/ufs/core/ufshcd.c | 36 ++++++++++++++++++++++++++++++++++++
include/ufs/ufshcd.h | 2 ++
include/ufs/ufshci.h | 1 +
3 files changed, 39 insertions(+)
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 0819ddafe7a6..c472bfdf071e 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -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) {
@@ -8119,6 +8124,35 @@ 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_rtt_set(struct ufs_hba *hba, u8 *desc_buf)
+{
+ 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, desc_buf[DEVICE_DESC_PARAM_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)
{
@@ -8278,6 +8312,8 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
if (hba->ext_iid_sup)
ufshcd_ext_iid_probe(hba, desc_buf);
+ ufshcd_rtt_set(hba, desc_buf);
+
/*
* ufshcd_read_string_desc returns size of the string
* reset the error value
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index bad88bd91995..d74bd2d67b06 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -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;
diff --git a/include/ufs/ufshci.h b/include/ufs/ufshci.h
index 385e1c6b8d60..c50f92bf2e1d 100644
--- a/include/ufs/ufshci.h
+++ b/include/ufs/ufshci.h
@@ -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,
--
2.42.0
On Fri, 2024-05-03 at 14:34 +0300, Avri Altman wrote:
> 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 <[email protected]>
Avri,
I was still curious about this 25% gain, so I will take a look. It
would be great if you could share more information about this.
Reviewed-by: Bean Huo <[email protected]>
> On Fri, 2024-05-03 at 14:34 +0300, Avri Altman wrote:
> > 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 <[email protected]>
>
>
> Avri,
>
> I was still curious about this 25% gain, so I will take a look. It would be great if
> you could share more information about this.
Thanks.
Those are just from early measurements.
But it perfectly makes sense to me: The rtt upiu works like Toyota's kanban cards.
And in gear 5 - there isn't enough cards...
Thanks,
Avri
>
>
>
> Reviewed-by: Bean Huo <[email protected]>
>
>
On Fri, 2024-05-03 at 14:34 +0300, Avri Altman wrote:
> 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 <[email protected]>
> Reviewed-by: Bean Huo <[email protected]>
> ---
> Changes since v1:
> - bMaxNumOfRTT is a Persistent attribute - do not override if it was
> written (Bean)
> ---
> drivers/ufs/core/ufshcd.c | 36 ++++++++++++++++++++++++++++++++++++
> include/ufs/ufshcd.h | 2 ++
> include/ufs/ufshci.h | 1 +
> 3 files changed, 39 insertions(+)
>
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 0819ddafe7a6..c472bfdf071e 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -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;
>
Hi Arvi.
Get nortt from NUTRS will have problem in mediatek platform.
The NUTRS in medatek platfrom is 32 or 64, but actually
host rtt support is only 2.
Please add new vops for host the set real rtt support.
Thanks.
Peter
> >
> > + hba->nortt = FIELD_GET(MASK_NUMBER_OUTSTANDING_RTT, hba-
> > >capabilities) + 1;
> >
>
> Hi Arvi.
>
> Get nortt from NUTRS will have problem in mediatek platform.
Not sure I follow - nortt has its own slot in the host capabilities - MASK_NUMBER_OUTSTANDING_RTT.
Thanks,
Avri
> The NUTRS in medatek platfrom is 32 or 64, but actually host rtt support is
> only 2.
> Please add new vops for host the set real rtt support.
>
> Thanks.
> Peter
>
On Mon, 2024-05-13 at 10:38 +0000, Avri Altman wrote:
>
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
> > >
> > > + hba->nortt = FIELD_GET(MASK_NUMBER_OUTSTANDING_RTT, hba-
> > > >capabilities) + 1;
> > >
> >
> > Hi Arvi.
> >
> > Get nortt from NUTRS will have problem in mediatek platform.
> Not sure I follow - nortt has its own slot in the host capabilities -
> MASK_NUMBER_OUTSTANDING_RTT.
>
> Thanks,
> Avri
>
Hi Avri,
Sorry, NORTTS value still cannot direct use in mediatek platform.
Hope we can have ops to set real host RTTs.
Thanks.
Peter
> > The NUTRS in medatek platfrom is 32 or 64, but actually host rtt
> support is
> > only 2.
> > Please add new vops for host the set real rtt support.
> >
> > Thanks.
> > Peter
> >
>
>
> On Mon, 2024-05-13 at 10:38 +0000, Avri Altman wrote:
> >
> > External email : Please do not click links or open attachments until
> > you have verified the sender or the content.
> > > >
> > > > + hba->nortt = FIELD_GET(MASK_NUMBER_OUTSTANDING_RTT, hba-
> > > > >capabilities) + 1;
> > > >
> > >
> > > Hi Arvi.
> > >
> > > Get nortt from NUTRS will have problem in mediatek platform.
> > Not sure I follow - nortt has its own slot in the host capabilities -
> > MASK_NUMBER_OUTSTANDING_RTT.
> >
> > Thanks,
> > Avri
> >
>
> Hi Avri,
>
> Sorry, NORTTS value still cannot direct use in mediatek platform.
> Hope we can have ops to set real host RTTs.
OK. Will allow platform vendors to override this default behavior.
Thanks,
Avri
>
> Thanks.
> Peter
>
>
>
>
> > > The NUTRS in medatek platfrom is 32 or 64, but actually host rtt
> > support is
> > > only 2.
> > > Please add new vops for host the set real rtt support.
> > >
> > > Thanks.
> > > Peter
> > >
> >
> >