[PATCH] usb: dwc3: core: fix clk_get_rate returning negative value

[Eugen Hristev]

Unlike it's Linux counterpart, clk_get_rate can return a negative value, -ve.
The driver does not take that into account, stores the rate into
an unsigned long, and if clk_get_rate fails, it will take into consideration
the actual value and wrongly program the hardware.
E.g. on error -2 (no such entry), the rate will be 18446744073709551614
and this will be subsequently used by the driver to program the DWC3
To fix this, exit the function if the value is negative.

Fixes: 6bae0eb5b8bd ("usb: dwc3: Calculate REFCLKPER based on reference clock")
Signed-off-by: Eugen Hristev <eugen.hristev at collabora.com>
---
 drivers/usb/dwc3/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 49f6a1900b01..5a8c29424578 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -138,7 +138,7 @@ static void dwc3_ref_clk_period(struct dwc3 *dwc)
 
 	if (dwc->ref_clk) {
 		rate = clk_get_rate(dwc->ref_clk);
-		if (!rate)
+		if (!rate || (long)rate < 0)
 			return;
 		period = NSEC_PER_SEC / rate;
 	} else {
-- 
2.34.1