[RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Ikjoon Jang]

xhci-mtk has 64 slots for periodic bandwidth calculations and each
slot represents byte budgets on a microframe. When an endpoint's
allocation sits on the boundary of the table, byte budgets' slot
should be rolled over but the current implementation doesn't.

This patch applies a 6 bits mask to the microframe index to handle
its rollover 64 slots and prevent out-of-bounds array access.

Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
---

 drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++------------------------
 drivers/usb/host/xhci-mtk.h     |  1 +
 2 files changed, 23 insertions(+), 57 deletions(-)

diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-mtk-sch.c
index 46cbf5d54f4f..ef16cd124343 100644
--- a/drivers/usb/host/xhci-mtk-sch.c
+++ b/drivers/usb/host/xhci-mtk-sch.c
@@ -411,18 +411,13 @@ static void setup_sch_info(struct xhci_ep_ctx *ep_ctx,
 static u32 get_max_bw(struct mu3h_sch_bw_info *sch_bw,
 	struct mu3h_sch_ep_info *sch_ep, u32 offset)
 {
-	u32 num_esit;
-	u32 max_bw = 0;
-	u32 bw;
-	int i;
-	int j;
-
-	num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
-	for (i = 0; i < num_esit; i++) {
-		u32 base = offset + i * sch_ep->esit;
+	u32 bw, max_bw = 0;
+	int i, j, idx;
 
+	for (i = 0; i < XHCI_MTK_MAX_ESIT; i += sch_ep->esit) {
 		for (j = 0; j < sch_ep->num_budget_microframes; j++) {
-			bw = sch_bw->bus_bw[base + j] +
+			idx = XHCI_MTK_BW_IDX(i + offset + j);
+			bw = sch_bw->bus_bw[idx] +
 					sch_ep->bw_budget_table[j];
 			if (bw > max_bw)
 				max_bw = bw;
@@ -434,20 +429,16 @@ static u32 get_max_bw(struct mu3h_sch_bw_info *sch_bw,
 static void update_bus_bw(struct mu3h_sch_bw_info *sch_bw,
 	struct mu3h_sch_ep_info *sch_ep, bool used)
 {
-	u32 num_esit;
-	u32 base;
-	int i;
-	int j;
+	int i, j, idx;
 
-	num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
-	for (i = 0; i < num_esit; i++) {
-		base = sch_ep->offset + i * sch_ep->esit;
+	for (i = 0; i < XHCI_MTK_MAX_ESIT; i += sch_ep->esit) {
 		for (j = 0; j < sch_ep->num_budget_microframes; j++) {
+			idx = XHCI_MTK_BW_IDX(i + sch_ep->offset + j);
 			if (used)
-				sch_bw->bus_bw[base + j] +=
+				sch_bw->bus_bw[idx] +=
 					sch_ep->bw_budget_table[j];
 			else
-				sch_bw->bus_bw[base + j] -=
+				sch_bw->bus_bw[idx] -=
 					sch_ep->bw_budget_table[j];
 		}
 	}
@@ -456,22 +447,18 @@ static void update_bus_bw(struct mu3h_sch_bw_info *sch_bw,
 static int check_fs_bus_bw(struct mu3h_sch_ep_info *sch_ep, int offset)
 {
 	struct mu3h_sch_tt *tt = sch_ep->sch_tt;
-	u32 num_esit, tmp;
-	int base;
-	int i, j;
+	u32 bw;
+	int i, j, idx;
 	u8 uframes = DIV_ROUND_UP(sch_ep->maxpkt, FS_PAYLOAD_MAX);
 
-	num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
-
 	if (sch_ep->ep_type == INT_IN_EP || sch_ep->ep_type == ISOC_IN_EP)
 		offset++;
 
-	for (i = 0; i < num_esit; i++) {
-		base = offset + i * sch_ep->esit;
-
+	for (i = 0; i < XHCI_MTK_MAX_ESIT; i += sch_ep->esit) {
 		for (j = 0; j < uframes; j++) {
-			tmp = tt->fs_bus_bw[base + j] + sch_ep->bw_cost_per_microframe;
-			if (tmp > FS_PAYLOAD_MAX)
+			idx = XHCI_MTK_BW_IDX(i + offset + j);
+			bw = tt->fs_bus_bw[idx] + sch_ep->bw_cost_per_microframe;
+			if (bw > FS_PAYLOAD_MAX)
 				return -ESCH_BW_OVERFLOW;
 		}
 	}
@@ -544,14 +531,11 @@ static int check_sch_tt(struct mu3h_sch_ep_info *sch_ep, u32 offset)
 static void update_sch_tt(struct mu3h_sch_ep_info *sch_ep, bool used)
 {
 	struct mu3h_sch_tt *tt = sch_ep->sch_tt;
-	u32 base, num_esit;
 	int bw_updated;
-	int i, j;
+	int i, j, idx;
 	int offset = sch_ep->offset;
 	u8 uframes = DIV_ROUND_UP(sch_ep->maxpkt, FS_PAYLOAD_MAX);
 
-	num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
-
 	if (used)
 		bw_updated = sch_ep->bw_cost_per_microframe;
 	else
@@ -560,11 +544,11 @@ static void update_sch_tt(struct mu3h_sch_ep_info *sch_ep, bool used)
 	if (sch_ep->ep_type == INT_IN_EP || sch_ep->ep_type == ISOC_IN_EP)
 		offset++;
 
-	for (i = 0; i < num_esit; i++) {
-		base = offset + i * sch_ep->esit;
-
-		for (j = 0; j < uframes; j++)
-			tt->fs_bus_bw[base + j] += bw_updated;
+	for (i = 0; i < XHCI_MTK_MAX_ESIT; i += sch_ep->esit) {
+		for (j = 0; j < uframes; j++) {
+			idx = XHCI_MTK_BW_IDX(i + offset + j);
+			tt->fs_bus_bw[idx] += bw_updated;
+		}
 	}
 
 	if (used)
@@ -586,25 +570,9 @@ static int load_ep_bw(struct mu3h_sch_bw_info *sch_bw,
 	return 0;
 }
 
-static u32 get_esit_boundary(struct mu3h_sch_ep_info *sch_ep)
-{
-	u32 boundary = sch_ep->esit;
-
-	if (sch_ep->sch_tt) { /* LS/FS with TT */
-		/* tune for CS */
-		if (sch_ep->ep_type != ISOC_OUT_EP)
-			boundary++;
-		else if (boundary > 1) /* normally esit >= 8 for FS/LS */
-			boundary--;
-	}
-
-	return boundary;
-}
-
 static int check_sch_bw(struct mu3h_sch_ep_info *sch_ep)
 {
 	struct mu3h_sch_bw_info *sch_bw = sch_ep->bw_info;
-	const u32 esit_boundary = get_esit_boundary(sch_ep);
 	const u32 bw_boundary = get_bw_boundary(sch_ep->speed);
 	u32 offset;
 	u32 worst_bw;
@@ -621,9 +589,6 @@ static int check_sch_bw(struct mu3h_sch_ep_info *sch_ep)
 		if (ret)
 			continue;
 
-		if ((offset + sch_ep->num_budget_microframes) > esit_boundary)
-			break;
-
 		worst_bw = get_max_bw(sch_bw, sch_ep, offset);
 		if (worst_bw > bw_boundary)
 			continue;
diff --git a/drivers/usb/host/xhci-mtk.h b/drivers/usb/host/xhci-mtk.h
index ddcf25524f67..f627941c4860 100644
--- a/drivers/usb/host/xhci-mtk.h
+++ b/drivers/usb/host/xhci-mtk.h
@@ -23,6 +23,7 @@
  * bandwidth to it.
  */
 #define XHCI_MTK_MAX_ESIT	64
+#define XHCI_MTK_BW_IDX(idx)	((idx) & 63)
 
 /**
  * @fs_bus_bw: array to keep track of bandwidth already used for FS
-- 
2.32.0.605.g8dce9f2422-goog

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Greg Kroah-Hartman]

On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> xhci-mtk has 64 slots for periodic bandwidth calculations and each
> slot represents byte budgets on a microframe. When an endpoint's
> allocation sits on the boundary of the table, byte budgets' slot
> should be rolled over but the current implementation doesn't.
> 
> This patch applies a 6 bits mask to the microframe index to handle
> its rollover 64 slots and prevent out-of-bounds array access.
> 
> Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> ---
> 
>  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++------------------------
>  drivers/usb/host/xhci-mtk.h     |  1 +
>  2 files changed, 23 insertions(+), 57 deletions(-)

Why is this "RFC"?  What needs to be addressed in this change before it
can be accepted?

thanks,

greg k-h

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Ikjoon Jang]

On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> > xhci-mtk has 64 slots for periodic bandwidth calculations and each
> > slot represents byte budgets on a microframe. When an endpoint's
> > allocation sits on the boundary of the table, byte budgets' slot
> > should be rolled over but the current implementation doesn't.
> >
> > This patch applies a 6 bits mask to the microframe index to handle
> > its rollover 64 slots and prevent out-of-bounds array access.
> >
> > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > ---
> >
> >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++------------------------
> >  drivers/usb/host/xhci-mtk.h     |  1 +
> >  2 files changed, 23 insertions(+), 57 deletions(-)
>
> Why is this "RFC"?  What needs to be addressed in this change before it
> can be accepted?

sorry, I had to mention why this is RFC:

I simply don't know about the details of the xhci-mtk internals.
It was okay from my tests with mt8173 and I think this will be harmless
as this is "better than before".

But when I removed get_esit_boundary(), I really have no idea why
it was there. I'm wondering if there was another reason of that function
other than just preventing out-of-bounds. Maybe chunfeng can answer this?

Thanks!

>
> thanks,
>
> greg k-h

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Chunfeng Yun (云春峰)]

On Mon, 2021-08-09 at 17:42 +0800, Ikjoon Jang wrote:
> On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > 
> > On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> > > xhci-mtk has 64 slots for periodic bandwidth calculations and
> > > each
> > > slot represents byte budgets on a microframe. When an endpoint's
> > > allocation sits on the boundary of the table, byte budgets' slot
> > > should be rolled over but the current implementation doesn't.
> > > 
> > > This patch applies a 6 bits mask to the microframe index to
> > > handle
> > > its rollover 64 slots and prevent out-of-bounds array access.
> > > 
> > > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > > ---
> > > 
> > >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++----------------
> > > --------
> > >  drivers/usb/host/xhci-mtk.h     |  1 +
> > >  2 files changed, 23 insertions(+), 57 deletions(-)
> > 
> > Why is this "RFC"?  What needs to be addressed in this change
> > before it
> > can be accepted?
> 
> sorry, I had to mention why this is RFC:
> 
> I simply don't know about the details of the xhci-mtk internals.
> It was okay from my tests with mt8173 and I think this will be
> harmless
> as this is "better than before".
> 
> But when I removed get_esit_boundary(), I really have no idea why
> it was there. I'm wondering if there was another reason of that
> function
> other than just preventing out-of-bounds. Maybe chunfeng can answer
> this?
We use @esit to prevent out-of-bounds array access. it's not a ring,
can't insert out-of-bounds value into head slot.

> 
> Thanks!
> 
> > 
> > thanks,
> > 
> > greg k-h

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Ikjoon Jang]

HI,

On Wed, Aug 11, 2021 at 5:02 PM Chunfeng Yun (云春峰)
<Chunfeng.Yun@mediatek.com> wrote:
>
> On Mon, 2021-08-09 at 17:42 +0800, Ikjoon Jang wrote:
> > On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> > > > xhci-mtk has 64 slots for periodic bandwidth calculations and
> > > > each
> > > > slot represents byte budgets on a microframe. When an endpoint's
> > > > allocation sits on the boundary of the table, byte budgets' slot
> > > > should be rolled over but the current implementation doesn't.
> > > >
> > > > This patch applies a 6 bits mask to the microframe index to
> > > > handle
> > > > its rollover 64 slots and prevent out-of-bounds array access.
> > > >
> > > > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > > > ---
> > > >
> > > >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++----------------
> > > > --------
> > > >  drivers/usb/host/xhci-mtk.h     |  1 +
> > > >  2 files changed, 23 insertions(+), 57 deletions(-)
> > >
> > > Why is this "RFC"?  What needs to be addressed in this change
> > > before it
> > > can be accepted?
> >
> > sorry, I had to mention why this is RFC:
> >
> > I simply don't know about the details of the xhci-mtk internals.
> > It was okay from my tests with mt8173 and I think this will be
> > harmless
> > as this is "better than before".
> >
> > But when I removed get_esit_boundary(), I really have no idea why
> > it was there. I'm wondering if there was another reason of that
> > function
> > other than just preventing out-of-bounds. Maybe chunfeng can answer
> > this?
> We use @esit to prevent out-of-bounds array access. it's not a ring,
> can't insert out-of-bounds value into head slot.

Thanks, so that function was only for out-of-bounds array access.
then I think we just can remove that function and use it as a ring.
Can you tell me _why_ it can't be used as a ring?

I think a transaction (e.g. esit_boundary = 7) can start its first SSPLIT
from Y_7 (offset = 7). But will that allocation be matched with this?

-               if ((offset + sch_ep->num_budget_microframes) > esit_boundary)
-                       break;

I mean I'm not sure why this is needed.

Until now, I couldn't find a way to accept the USB audio headset
with a configuration of { INT-IN 64 + ISOC-OUT 384 + ISOC-IN 192 }
without this patch.

>
> >
> > Thanks!
> >
> > >
> > > thanks,
> > >
> > > greg k-h

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Chunfeng Yun (云春峰)]

On Thu, 2021-08-12 at 17:31 +0800, Ikjoon Jang wrote:
> HI,
> 
> On Wed, Aug 11, 2021 at 5:02 PM Chunfeng Yun (云春峰)
> <Chunfeng.Yun@mediatek.com> wrote:
> > 
> > On Mon, 2021-08-09 at 17:42 +0800, Ikjoon Jang wrote:
> > > On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > > 
> > > > On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> > > > > xhci-mtk has 64 slots for periodic bandwidth calculations and
> > > > > each
> > > > > slot represents byte budgets on a microframe. When an
> > > > > endpoint's
> > > > > allocation sits on the boundary of the table, byte budgets'
> > > > > slot
> > > > > should be rolled over but the current implementation doesn't.
> > > > > 
> > > > > This patch applies a 6 bits mask to the microframe index to
> > > > > handle
> > > > > its rollover 64 slots and prevent out-of-bounds array access.
> > > > > 
> > > > > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > > > > ---
> > > > > 
> > > > >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++------------
> > > > > ----
> > > > > --------
> > > > >  drivers/usb/host/xhci-mtk.h     |  1 +
> > > > >  2 files changed, 23 insertions(+), 57 deletions(-)
> > > > 
> > > > Why is this "RFC"?  What needs to be addressed in this change
> > > > before it
> > > > can be accepted?
> > > 
> > > sorry, I had to mention why this is RFC:
> > > 
> > > I simply don't know about the details of the xhci-mtk internals.
> > > It was okay from my tests with mt8173 and I think this will be
> > > harmless
> > > as this is "better than before".
> > > 
> > > But when I removed get_esit_boundary(), I really have no idea why
> > > it was there. I'm wondering if there was another reason of that
> > > function
> > > other than just preventing out-of-bounds. Maybe chunfeng can
> > > answer
> > > this?
> > 
> > We use @esit to prevent out-of-bounds array access. it's not a
> > ring,
> > can't insert out-of-bounds value into head slot.
> 
> Thanks, so that function was only for out-of-bounds array access.
> then I think we just can remove that function and use it as a ring.
> Can you tell me _why_ it can't be used as a ring?
Treat it as a period, roll over slot equals to put it into the next
period.

> 
> I think a transaction (e.g. esit_boundary = 7) can start its first
> SSPLIT
> from Y_7 (offset = 7). But will that allocation be matched with this?
> 
> -               if ((offset + sch_ep->num_budget_microframes) >
> esit_boundary)
> -                       break;
> 
> I mean I'm not sure why this is needed.
Prevent out-of-bounds.

> 
> Until now, I couldn't find a way to accept the USB audio headset
> with a configuration of { INT-IN 64 + ISOC-OUT 384 + ISOC-IN 192 }
> without this patch.
what is the interval value of each endpoint?

> 
> > 
> > > 
> > > Thanks!
> > > 
> > > > 
> > > > thanks,
> > > > 
> > > > greg k-h

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Ikjoon Jang]

oops sorry I sent a prior mail in HTML.
Resend this mail in plain text.

On Thu, Aug 12, 2021 at 7:49 PM Chunfeng Yun (云春峰)
<Chunfeng.Yun@mediatek.com> wrote:
>
> On Thu, 2021-08-12 at 17:31 +0800, Ikjoon Jang wrote:
> > HI,
> >
> > On Wed, Aug 11, 2021 at 5:02 PM Chunfeng Yun (云春峰)
> > <Chunfeng.Yun@mediatek.com> wrote:
> > >
> > > On Mon, 2021-08-09 at 17:42 +0800, Ikjoon Jang wrote:
> > > > On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
> > > > <gregkh@linuxfoundation.org> wrote:
> > > > >
> > > > > On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> > > > > > xhci-mtk has 64 slots for periodic bandwidth calculations and
> > > > > > each
> > > > > > slot represents byte budgets on a microframe. When an
> > > > > > endpoint's
> > > > > > allocation sits on the boundary of the table, byte budgets'
> > > > > > slot
> > > > > > should be rolled over but the current implementation doesn't.
> > > > > >
> > > > > > This patch applies a 6 bits mask to the microframe index to
> > > > > > handle
> > > > > > its rollover 64 slots and prevent out-of-bounds array access.
> > > > > >
> > > > > > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > > > > > ---
> > > > > >
> > > > > >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++------------
> > > > > > ----
> > > > > > --------
> > > > > >  drivers/usb/host/xhci-mtk.h     |  1 +
> > > > > >  2 files changed, 23 insertions(+), 57 deletions(-)
> > > > >
> > > > > Why is this "RFC"?  What needs to be addressed in this change
> > > > > before it
> > > > > can be accepted?
> > > >
> > > > sorry, I had to mention why this is RFC:
> > > >
> > > > I simply don't know about the details of the xhci-mtk internals.
> > > > It was okay from my tests with mt8173 and I think this will be
> > > > harmless
> > > > as this is "better than before".
> > > >
> > > > But when I removed get_esit_boundary(), I really have no idea why
> > > > it was there. I'm wondering if there was another reason of that
> > > > function
> > > > other than just preventing out-of-bounds. Maybe chunfeng can
> > > > answer
> > > > this?
> > >
> > > We use @esit to prevent out-of-bounds array access. it's not a
> > > ring,
> > > can't insert out-of-bounds value into head slot.
> >
> > Thanks, so that function was only for out-of-bounds array access.
> > then I think we just can remove that function and use it as a ring.
> > Can you tell me _why_ it can't be used as a ring?
> Treat it as a period, roll over slot equals to put it into the next
> period.
>
> >
> > I think a transaction (e.g. esit_boundary = 7) can start its first
> > SSPLIT
> > from Y_7 (offset = 7). But will that allocation be matched with this?
> >
> > -               if ((offset + sch_ep->num_budget_microframes) >
> > esit_boundary)
> > -                       break;
> >
> > I mean I'm not sure why this is needed.
> Prevent out-of-bounds.
>
> >
> > Until now, I couldn't find a way to accept the USB audio headset
> > with a configuration of { INT-IN 64 + ISOC-OUT 384 + ISOC-IN 192 }
> > without this patch.
> what is the interval value of each endpoint?

interrupt ep is 2ms and others are 1ms
Thanks.

>
> >
> > >
> > > >
> > > > Thanks!
> > > >
> > > > >
> > > > > thanks,
> > > > >
> > > > > greg k-h

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Ikjoon Jang]

Hi Chunfeng,

On Thu, Aug 12, 2021 at 7:49 PM Chunfeng Yun (云春峰)
<Chunfeng.Yun@mediatek.com> wrote:
>
> On Thu, 2021-08-12 at 17:31 +0800, Ikjoon Jang wrote:
> > HI,
> >
> > On Wed, Aug 11, 2021 at 5:02 PM Chunfeng Yun (云春峰)
> > <Chunfeng.Yun@mediatek.com> wrote:
> > >
> > > On Mon, 2021-08-09 at 17:42 +0800, Ikjoon Jang wrote:
> > > > On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
> > > > <gregkh@linuxfoundation.org> wrote:
> > > > >
> > > > > On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang wrote:
> > > > > > xhci-mtk has 64 slots for periodic bandwidth calculations and
> > > > > > each
> > > > > > slot represents byte budgets on a microframe. When an
> > > > > > endpoint's
> > > > > > allocation sits on the boundary of the table, byte budgets'
> > > > > > slot
> > > > > > should be rolled over but the current implementation doesn't.
> > > > > >
> > > > > > This patch applies a 6 bits mask to the microframe index to
> > > > > > handle
> > > > > > its rollover 64 slots and prevent out-of-bounds array access.
> > > > > >
> > > > > > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > > > > > ---
> > > > > >
> > > > > >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++------------
> > > > > > ----
> > > > > > --------
> > > > > >  drivers/usb/host/xhci-mtk.h     |  1 +
> > > > > >  2 files changed, 23 insertions(+), 57 deletions(-)
> > > > >
> > > > > Why is this "RFC"?  What needs to be addressed in this change
> > > > > before it
> > > > > can be accepted?
> > > >
> > > > sorry, I had to mention why this is RFC:
> > > >
> > > > I simply don't know about the details of the xhci-mtk internals.
> > > > It was okay from my tests with mt8173 and I think this will be
> > > > harmless
> > > > as this is "better than before".
> > > >
> > > > But when I removed get_esit_boundary(), I really have no idea why
> > > > it was there. I'm wondering if there was another reason of that
> > > > function
> > > > other than just preventing out-of-bounds. Maybe chunfeng can
> > > > answer
> > > > this?
> > >
> > > We use @esit to prevent out-of-bounds array access. it's not a
> > > ring,
> > > can't insert out-of-bounds value into head slot.
> >
> > Thanks, so that function was only for out-of-bounds array access.
> > then I think we just can remove that function and use it as a ring.
> > Can you tell me _why_ it can't be used as a ring?
> Treat it as a period, roll over slot equals to put it into the next
> period.
>
> >
> > I think a transaction (e.g. esit_boundary = 7) can start its first
> > SSPLIT
> > from Y_7 (offset = 7). But will that allocation be matched with this?
> >
> > -               if ((offset + sch_ep->num_budget_microframes) >
> > esit_boundary)
> > -                       break;
> >
> > I mean I'm not sure why this is needed.
> Prevent out-of-bounds.

If it was for preventing drivers from out-of-bound array access,
I couldn't find any reasons why we cannot remove the above lines.
So can I know if it was just for preventing xhci-mtk drivers from
out-of-bounds array access?

If xhci-mtk HC itself can continue the transaction from Y_7 to (Y+1)_n;
including the case of Y==63, I think it's just okay to rollover to (Y+1).

If it's prohibited by xhci-mtk hw, or if you think this patch is not
allowed by any other reasons, can you please  tell me what
kinds of problems can happen with this patch?

Otherwise, please consider minimizing the bw constraints from
xhci-mtk-sch on your side. Note that we're still having other usb
audio headsets which cannot be configured with xhci-mtk
even with this patch.

Thanks.

>
> >
> > Until now, I couldn't find a way to accept the USB audio headset
> > with a configuration of { INT-IN 64 + ISOC-OUT 384 + ISOC-IN 192 }
> > without this patch.
> what is the interval value of each endpoint?
>
> >
> > >
> > > >
> > > > Thanks!
> > > >
> > > > >
> > > > > thanks,
> > > > >
> > > > > greg k-h

Re: [RFC PATCH] usb: xhci-mtk: handle bandwidth table rollover

[Chunfeng Yun (云春峰)]

On Wed, 2021-08-18 at 10:43 +0800, Ikjoon Jang wrote:
> Hi Chunfeng,
> 
> On Thu, Aug 12, 2021 at 7:49 PM Chunfeng Yun (云春峰)
> <Chunfeng.Yun@mediatek.com> wrote:
> > 
> > On Thu, 2021-08-12 at 17:31 +0800, Ikjoon Jang wrote:
> > > HI,
> > > 
> > > On Wed, Aug 11, 2021 at 5:02 PM Chunfeng Yun (云春峰)
> > > <Chunfeng.Yun@mediatek.com> wrote:
> > > > 
> > > > On Mon, 2021-08-09 at 17:42 +0800, Ikjoon Jang wrote:
> > > > > On Mon, Aug 9, 2021 at 5:11 PM Greg Kroah-Hartman
> > > > > <gregkh@linuxfoundation.org> wrote:
> > > > > > 
> > > > > > On Mon, Aug 09, 2021 at 04:59:29PM +0800, Ikjoon Jang
> > > > > > wrote:
> > > > > > > xhci-mtk has 64 slots for periodic bandwidth calculations
> > > > > > > and
> > > > > > > each
> > > > > > > slot represents byte budgets on a microframe. When an
> > > > > > > endpoint's
> > > > > > > allocation sits on the boundary of the table, byte
> > > > > > > budgets'
> > > > > > > slot
> > > > > > > should be rolled over but the current implementation
> > > > > > > doesn't.
> > > > > > > 
> > > > > > > This patch applies a 6 bits mask to the microframe index
> > > > > > > to
> > > > > > > handle
> > > > > > > its rollover 64 slots and prevent out-of-bounds array
> > > > > > > access.
> > > > > > > 
> > > > > > > Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> > > > > > > ---
> > > > > > > 
> > > > > > >  drivers/usb/host/xhci-mtk-sch.c | 79 +++++++++--------
> > > > > > > ----
> > > > > > > ----
> > > > > > > --------
> > > > > > >  drivers/usb/host/xhci-mtk.h     |  1 +
> > > > > > >  2 files changed, 23 insertions(+), 57 deletions(-)
> > > > > > 
> > > > > > Why is this "RFC"?  What needs to be addressed in this
> > > > > > change
> > > > > > before it
> > > > > > can be accepted?
> > > > > 
> > > > > sorry, I had to mention why this is RFC:
> > > > > 
> > > > > I simply don't know about the details of the xhci-mtk
> > > > > internals.
> > > > > It was okay from my tests with mt8173 and I think this will
> > > > > be
> > > > > harmless
> > > > > as this is "better than before".
> > > > > 
> > > > > But when I removed get_esit_boundary(), I really have no idea
> > > > > why
> > > > > it was there. I'm wondering if there was another reason of
> > > > > that
> > > > > function
> > > > > other than just preventing out-of-bounds. Maybe chunfeng can
> > > > > answer
> > > > > this?
> > > > 
> > > > We use @esit to prevent out-of-bounds array access. it's not a
> > > > ring,
> > > > can't insert out-of-bounds value into head slot.
> > > 
> > > Thanks, so that function was only for out-of-bounds array access.
> > > then I think we just can remove that function and use it as a
> > > ring.
> > > Can you tell me _why_ it can't be used as a ring?
> > 
> > Treat it as a period, roll over slot equals to put it into the next
> > period.
> > 
> > > 
> > > I think a transaction (e.g. esit_boundary = 7) can start its
> > > first
> > > SSPLIT
> > > from Y_7 (offset = 7). But will that allocation be matched with
> > > this?
> > > 
> > > -               if ((offset + sch_ep->num_budget_microframes) >
> > > esit_boundary)
> > > -                       break;
> > > 
> > > I mean I'm not sure why this is needed.
> > 
> > Prevent out-of-bounds.
> 
> If it was for preventing drivers from out-of-bound array access,
> I couldn't find any reasons why we cannot remove the above lines.
> So can I know if it was just for preventing xhci-mtk drivers from
> out-of-bounds array access?
Due to it use an array to calculate bandwidth, if use ring, can remove
it.

> 
> If xhci-mtk HC itself can continue the transaction from Y_7 to
> (Y+1)_n;
> including the case of Y==63, I think it's just okay to rollover to
> (Y+1).
> 
> If it's prohibited by xhci-mtk hw, or if you think this patch is not
> allowed by any other reasons, can you please  tell me what
> kinds of problems can happen with this patch?
Seems sw limitation, or avoid repeated calculation;
I'll change it as a ring, and do some tests.
> 
> Otherwise, please consider minimizing the bw constraints from
> xhci-mtk-sch on your side. Note that we're still having other usb
> audio headsets which cannot be configured with xhci-mtk
> even with this patch.
Ok, try my best to do it, thanks a lot

> 
> Thanks.
> 
> > 
> > > 
> > > Until now, I couldn't find a way to accept the USB audio headset
> > > with a configuration of { INT-IN 64 + ISOC-OUT 384 + ISOC-IN 192
> > > }
> > > without this patch.
> > 
> > what is the interval value of each endpoint?
> > 
> > > 
> > > > 
> > > > > 
> > > > > Thanks!
> > > > > 
> > > > > > 
> > > > > > thanks,
> > > > > > 
> > > > > > greg k-h