This is a note to let you know that I've just added the patch titled
usb: dwc2: Skip clock gating on Samsung SoCs
to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From c4a0f7a6ab5417eb6105b0e1d7e6e67f6ef7d4e5 Mon Sep 17 00:00:00 2001
From: Marek Szyprowski m.szyprowski@samsung.com Date: Fri, 16 Jul 2021 07:01:27 +0200 Subject: usb: dwc2: Skip clock gating on Samsung SoCs
Commit 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.") changed the way the driver handles power down modes in a such way that it uses clock gating when no other power down mode is available.
This however doesn't work well on the DWC2 implementation used on the Samsung SoCs. When a clock gating is enabled, system hangs. It looks that the proper clock gating requires some additional glue code in the shared USB2 PHY and/or Samsung glue code for the DWC2. To restore driver operation on the Samsung SoCs simply skip enabling clock gating mode until one finds what is really needed to make it working reliably.
Fixes: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.") Cc: stable stable@vger.kernel.org Acked-by: Krzysztof Kozlowski krzysztof.kozlowski@canonical.com Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Link: https://lore.kernel.org/r/20210716050127.4406-1-m.szyprowski@samsung.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/dwc2/core.h | 4 ++++ drivers/usb/dwc2/core_intr.c | 3 ++- drivers/usb/dwc2/hcd.c | 6 ++++-- drivers/usb/dwc2/params.c | 1 + 4 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h index ab6b815e0089..483de2bbfaab 100644 --- a/drivers/usb/dwc2/core.h +++ b/drivers/usb/dwc2/core.h @@ -383,6 +383,9 @@ enum dwc2_ep0_state { * 0 - No (default) * 1 - Partial power down * 2 - Hibernation + * @no_clock_gating: Specifies whether to avoid clock gating feature. + * 0 - No (use clock gating) + * 1 - Yes (avoid it) * @lpm: Enable LPM support. * 0 - No * 1 - Yes @@ -480,6 +483,7 @@ struct dwc2_core_params { #define DWC2_POWER_DOWN_PARAM_NONE 0 #define DWC2_POWER_DOWN_PARAM_PARTIAL 1 #define DWC2_POWER_DOWN_PARAM_HIBERNATION 2 + bool no_clock_gating;
bool lpm; bool lpm_clock_gating; diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c index a5ab03808da6..a5c52b237e72 100644 --- a/drivers/usb/dwc2/core_intr.c +++ b/drivers/usb/dwc2/core_intr.c @@ -556,7 +556,8 @@ static void dwc2_handle_usb_suspend_intr(struct dwc2_hsotg *hsotg) * If neither hibernation nor partial power down are supported, * clock gating is used to save power. */ - dwc2_gadget_enter_clock_gating(hsotg); + if (!hsotg->params.no_clock_gating) + dwc2_gadget_enter_clock_gating(hsotg); }
/* diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c index 035d4911a3c3..2a7828971d05 100644 --- a/drivers/usb/dwc2/hcd.c +++ b/drivers/usb/dwc2/hcd.c @@ -3338,7 +3338,8 @@ int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex) * If not hibernation nor partial power down are supported, * clock gating is used to save power. */ - dwc2_host_enter_clock_gating(hsotg); + if (!hsotg->params.no_clock_gating) + dwc2_host_enter_clock_gating(hsotg); break; }
@@ -4402,7 +4403,8 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd) * If not hibernation nor partial power down are supported, * clock gating is used to save power. */ - dwc2_host_enter_clock_gating(hsotg); + if (!hsotg->params.no_clock_gating) + dwc2_host_enter_clock_gating(hsotg);
/* After entering suspend, hardware is not accessible */ clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags); diff --git a/drivers/usb/dwc2/params.c b/drivers/usb/dwc2/params.c index 67c5eb140232..59e119345994 100644 --- a/drivers/usb/dwc2/params.c +++ b/drivers/usb/dwc2/params.c @@ -76,6 +76,7 @@ static void dwc2_set_s3c6400_params(struct dwc2_hsotg *hsotg) struct dwc2_core_params *p = &hsotg->params;
p->power_down = DWC2_POWER_DOWN_PARAM_NONE; + p->no_clock_gating = true; p->phy_utmi_width = 8; }