[PATCH] dwc3: Get the ref clock from the child node(dwc3)

[PATCH] dwc3: Get the ref clock from the child node(dwc3)

[Venkatesh Yadav Abbarapu]

Currently the parent node(dwc3) ref_clk is updated to the
dwc3->ref_clk, but we need to update the child node(dwc3)
"ref" clock to the dwc3->ref_clk.
For versal SOC, the parent node(usb) ref_clk is updated to dwc3->ref_clk
which is USB3_DUAL_REF, whereas it should contain the child node(dwc3)
"ref" clk i.e., USB0_BUS_REF. With this once we trigger "usb start"
the device is crashing.
For ZynqMP SOC, crash is not observed because the parent node(usb)
ref_clk and the child node(dwc3) "ref" clk is pointing to same
USB3_DUAL_REF clock.
Fix this by directly updating the child node(dwc3) "ref" clk to
dwc3->ref_clk from the dwc3_of_parse() function.

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
---
TBD: Need to port the clocks patch from linux kernel
[ Sean Anderson:Ported from Linux kernel commit
 	33fb697ec7e5 ("usb: dwc3: Get clocks individually") ]
---
 drivers/usb/dwc3/core.c         |  4 +++-
 drivers/usb/dwc3/dwc3-generic.c | 18 ++++++++++--------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index c80f2d0a53..3667691651 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1105,7 +1105,9 @@ void dwc3_of_parse(struct dwc3 *dwc)
 		| (dwc->is_utmi_l1_suspend << 4);
 
 	dev_read_u32(dev, "snps,quirk-frame-length-adjustment", &dwc->fladj);
-
+	dwc->ref_clk = devm_clk_get_optional(dev, "ref");
+	if (IS_ERR(dwc->ref_clk))
+		dev_err(dev, "dwc3 ref clock not found\n");
 	/*
 	 * Handle property "snps,incr-burst-type-adjustment".
 	 * Get the number of value from this property:
diff --git a/drivers/usb/dwc3/dwc3-generic.c b/drivers/usb/dwc3/dwc3-generic.c
index 66da5a8d6f..f2c512715c 100644
--- a/drivers/usb/dwc3/dwc3-generic.c
+++ b/drivers/usb/dwc3/dwc3-generic.c
@@ -75,18 +75,20 @@ static int dwc3_generic_probe(struct udevice *dev,
 	 * with the top level node as that seems to be used in majority of DTs
 	 * to reference the clock.
 	 */
-	node = dev_ofnode(dev->parent);
-	index = ofnode_stringlist_search(node, "clock-names", "ref");
-	if (index < 0)
-		index = ofnode_stringlist_search(node, "clock-names", "ref_clk");
-	if (index < 0) {
-		node = dev_ofnode(dev);
+	if (!IS_ENABLED(CONFIG_ARCH_VERSAL)) {
+		node = dev_ofnode(dev->parent);
 		index = ofnode_stringlist_search(node, "clock-names", "ref");
 		if (index < 0)
 			index = ofnode_stringlist_search(node, "clock-names", "ref_clk");
+		if (index < 0) {
+			node = dev_ofnode(dev);
+			index = ofnode_stringlist_search(node, "clock-names", "ref");
+			if (index < 0)
+				index = ofnode_stringlist_search(node, "clock-names", "ref_clk");
+		}
+		if (index >= 0)
+			dwc3->ref_clk = &glue->clks.clks[index];
 	}
-	if (index >= 0)
-		dwc3->ref_clk = &glue->clks.clks[index];
 #endif
 
 	/*
-- 
2.17.1

Re: [PATCH] dwc3: Get the ref clock from the child node(dwc3)

[Marek Vasut]

On 5/9/23 06:11, Venkatesh Yadav Abbarapu wrote:
> Currently the parent node(dwc3) ref_clk is updated to the
> dwc3->ref_clk, but we need to update the child node(dwc3)
> "ref" clock to the dwc3->ref_clk.
> For versal SOC, the parent node(usb) ref_clk is updated to dwc3->ref_clk
> which is USB3_DUAL_REF, whereas it should contain the child node(dwc3)
> "ref" clk i.e., USB0_BUS_REF. With this once we trigger "usb start"
> the device is crashing.
> For ZynqMP SOC, crash is not observed because the parent node(usb)
> ref_clk and the child node(dwc3) "ref" clk is pointing to same
> USB3_DUAL_REF clock.
> Fix this by directly updating the child node(dwc3) "ref" clk to
> dwc3->ref_clk from the dwc3_of_parse() function.
> 
> Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
> ---
> TBD: Need to port the clocks patch from linux kernel

I will wait for a proper backport of all the missing patches, not just a 
subset.

Also, this is clearly a work-in-progress patch, please mark it as 
"[RFC]" next time.