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[v3,2/2] usb: dwc3: Fix DRD mode change sequence following programming guide

Message ID 20210108015115.27920-2-john.stultz@linaro.org
State New
Headers show
Series [v3,1/2] usb: dwc3: Trigger a GCTL soft reset when switching modes in DRD | expand

Commit Message

John Stultz Jan. 8, 2021, 1:51 a.m. UTC
In reviewing the previous patch, Thinh Nguyen pointed out that
the DRD mode change sequence should be like the following when
switching from host -> device according to the programming guide
(for all DRD IPs):
1. Reset controller with GCTL.CoreSoftReset
2. Set GCTL.PrtCapDir(device)
3. Soft reset with DCTL.CSftRst
4. Then follow up with the initializing registers sequence

The current code does:
a. Soft reset with DCTL.CSftRst on driver probe
b. Reset controller with GCTL.CoreSoftReset (added in previous
c. Set GCTL.PrtCapDir(device)
d. < missing DCTL.CSftRst >
e. Then follow up with initializing registers sequence

So this patch adds the DCTL.CSftRst soft reset that was currently
missing from the dwc3 mode switching.

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Tejas Joglekar <tejas.joglekar@synopsys.com>
Cc: Yang Fei <fei.yang@intel.com>
Cc: YongQin Liu <yongqin.liu@linaro.org>
Cc: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Cc: Thinh Nguyen <thinhn@synopsys.com>
Cc: Jun Li <lijun.kernel@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Signed-off-by: John Stultz <john.stultz@linaro.org>

Feedback would be appreciated. I'm a little worried I should be
conditionalizing the DCTL.CSftRst on DRD mode controllers, but
I'm really not sure what the right thing to do is for non-DRD
mode controllers.
 drivers/usb/dwc3/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff mbox series


diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index b6a6b90eb2d5..71f8b07ecb99 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -40,6 +40,8 @@ 
 #define DWC3_DEFAULT_AUTOSUSPEND_DELAY	5000 /* ms */
+static int dwc3_core_soft_reset(struct dwc3 *dwc);
  * dwc3_get_dr_mode - Validates and sets dr_mode
  * @dwc: pointer to our context structure
@@ -177,6 +179,7 @@  static void __dwc3_set_mode(struct work_struct *work)
 	dwc3_set_prtcap(dwc, dwc->desired_dr_role);
+	dwc3_core_soft_reset(dwc);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 	switch (dwc->desired_dr_role) {