Thread (16 messages) 16 messages, 5 authors, 2021-08-13

Re: [PATCH v2 4/6] usb: dwc3: reference clock period configuration

From: Baruch Siach <baruch@tkos.co.il>
Date: 2021-08-04 14:22:33
Also in: linux-arm-kernel, linux-arm-msm, linux-phy, linux-usb

Hi Felipe,

On Wed, Aug 04 2021, Felipe Balbi wrote:
Baruch Siach [off-list ref] writes:
quoted
@@ -1371,6 +1398,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				    &dwc->hsphy_interface);
 	device_property_read_u32(dev, "snps,quirk-frame-length-adjustment",
 				 &dwc->fladj);
+	device_property_read_u32(dev, "snps,ref-clock-period",
+				 &dwc->ref_clk_per);
I wonder if it would make more sense to pass an actual clock reference
here. If valid, then reconfigure the period to the value returned by
clk_get_rate(). It would avoid yet another DT binding. If we make the
clock optional, then we won't affect any other platforms. The clock
itself could be a regular fixed clock node.
Thinh Nguyen asked to add a dedicated DT property. He explained that
clk_get_rate() does not work for PCI hosted dwc3. This is the most
complete summary of the discussion:

  https://lore.kernel.org/r/c797e9cb-cae6-c0b6-5714-169c2ad79d32@synopsys.com (local)

baruch

-- 
                                                     ~. .~   Tk Open Systems
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   - baruch@tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -
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