Re: [PATCH 7/8] arm64: dts: qcom: ipq9574: Add USB related nodes
From: Dmitry Baryshkov
Date: Tue Mar 07 2023 - 06:51:25 EST
On 07/03/2023 08:36, Varadarajan Narayanan wrote:
On 3/6/2023 5:21 PM, Dmitry Baryshkov wrote:
On 06/03/2023 13:26, Varadarajan Narayanan wrote:
Dmitry,
On 3/2/2023 9:52 PM, Dmitry Baryshkov wrote:
On Thu, 2 Mar 2023 at 11:57, Varadarajan Narayanan
<quic_varada@xxxxxxxxxxx> wrote:
Add USB phy and controller related nodes
Signed-off-by: Varadarajan Narayanan <quic_varada@xxxxxxxxxxx>
---
arch/arm64/boot/dts/qcom/ipq9574.dtsi | 92
+++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)
diff --git a/arch/arm64/boot/dts/qcom/ipq9574.dtsi
b/arch/arm64/boot/dts/qcom/ipq9574.dtsi
index 2bb4053..319b5bd 100644
--- a/arch/arm64/boot/dts/qcom/ipq9574.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq9574.dtsi
[skipped]
+ usb3: usb3@8A00000 {
You know the drill. This node is in the wrong place.
+ compatible = "qcom,dwc3";
+ reg = <0x8AF8800 0x400>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+
+ clocks = <&gcc GCC_SNOC_USB_CLK>,
+ <&gcc GCC_ANOC_USB_AXI_CLK>,
+ <&gcc GCC_USB0_MASTER_CLK>,
+ <&gcc GCC_USB0_SLEEP_CLK>,
+ <&gcc GCC_USB0_MOCK_UTMI_CLK>;
+
+ clock-names = "sys_noc_axi",
+ "anoc_axi",
+ "master",
+ "sleep",
+ "mock_utmi";
Please fix the indentation of the lists.
+
+ assigned-clocks = <&gcc GCC_SNOC_USB_CLK>,
+ <&gcc GCC_ANOC_USB_AXI_CLK>,
Why do you assign clock rates to the NOC clocks? Should they be set
using the interconnect instead?
The SNOC and ANOC run at a fixed speed of 350MHz and 342MHz
respectively and are not scaled. These clocks are for the interface
between the USB block and the SNOC/ANOC. Do we still need to use
interconnect?
Maybe I misunderstand something here. If the snoc and anoc speeds are
at 350 MHz and 342 MHz, why do you assign clock-rates of 200 MHz?
Is it enough to call clk_prepare_enable() for these clocks or the rate
really needs to be set?
The rate of 200MHz is not being set for the SNOC/ANOC. It is for the
NIU that connects the USB and SNOC/ANOC. The reason for setting the
rate to 200MHz is to configure the RCG parent for these interface
clocks. That said can we configure this RCG standalone in the driver
and enable these clocks?
We discussed this separately with Georgi Djakov. Let me quote his IRC
message: "it sounds like this is for USB port that connects to the NOC.
if bandwidth scaling is not needed (or other interconnect
configuration), then maybe this can go without interconnect provider
driver."
However as we discover more and more about this platform (e.g. PCIe
using the aggre_noc region to setup some magic registers, see [1]), I'm
more and more biased towards suggesting implementing the interconnect
driver to setup all these tiny little things. With the DT tree being an
ABI, it is much preferable to overestimate the needs rather than
underestimating them (and having to cope with the backwards
compatibility issues).
Generally I think that PCIe/USB/whatever should not poke into NoC
registers or NoC/NIU clocks directly (because this is a very
platform-specific item). Rather than that it should tell the
icc/opp/whatever subsystem, "please configure the SoC for me to work".
[1]
https://lore.kernel.org/linux-arm-msm/30cf9717-dcca-e984-c506-c71b7f8e32cd@xxxxxxxxxxx/
Thanks
Varada
+ <&gcc GCC_USB0_MASTER_CLK>,
+ <&gcc
GCC_USB0_MOCK_UTMI_CLK>;
+ assigned-clock-rates = <200000000>,
+ <200000000>,
+ <200000000>,
+ <24000000>;
+
+ resets = <&gcc GCC_USB_BCR>;
+ status = "disabled";
+
+ dwc_0: dwc3@8A00000 {
+ compatible = "snps,dwc3";
+ reg = <0x8A00000 0xcd00>;
+ clock-names = "ref";
+ clocks = <&gcc
GCC_USB0_MOCK_UTMI_CLK>;
clocks before clock-names
+ interrupts = <GIC_SPI 140 IRQ_TYPE_LEVEL_HIGH>;
+ phys = <&qusb_phy_0>, <&usb0_ssphy>;
+ phy-names = "usb2-phy", "usb3-phy";
+ tx-fifo-resize;
+ snps,dis_ep_cache_eviction;
+ snps,is-utmi-l1-suspend;
+ snps,hird-threshold = /bits/ 8 <0x0>;
+ snps,dis_u2_susphy_quirk;
+ snps,dis_u3_susphy_quirk;
+ snps,quirk-frame-length-adjustment = <0x0A87F0A0>;
+ dr_mode = "host";
+ };
+ };
+
pcie0_phy: phy@84000 {
compatible =
"qcom,ipq9574-qmp-gen3x1-pcie-phy";
reg = <0x00084000 0x1bc>; /* Serdes PLL */
--
2.7.4
Will address these and post a new revision.
Thanks
Varada
--
With best wishes
Dmitry