linux-kernel - Re: [PATCH v2 4/4] phy: qcom: phy-qcom-snps-eusb2: Add extra register write for Milos

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Message-ID: <a2567891-1dd4-44ff-9853-6f9a451f0a74@oss.qualcomm.com>
Date: Thu, 10 Jul 2025 14:29:44 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Luca Weiss <luca.weiss@...rphone.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Wesley Cheng <quic_wcheng@...cinc.com>, Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Abel Vesa <abel.vesa@...aro.org>
Cc: ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-phy@...ts.infradead.org,
        Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH v2 4/4] phy: qcom: phy-qcom-snps-eusb2: Add extra register
 write for Milos

On 7/10/25 2:25 PM, Luca Weiss wrote:
> On Thu Jul 10, 2025 at 2:10 PM CEST, Konrad Dybcio wrote:
>> On 7/9/25 11:18 AM, Luca Weiss wrote:
>>> As per the downstream devicetree for Milos, add a register write for
>>> QCOM_USB_PHY_CFG_CTRL_1 as per the "eUSB2 HPG version 1.0.2 update".
>>>
>>> Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>
>>> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
>>> ---
>>> The downstream driver supports an arbitrary extra init sequence via
>>> qcom,param-override-seq.
>>>
>>> volcano-usb.dtsi has the following which is implemented in this patch:
>>>
>>>     /* eUSB2 HPG version 1.0.2 update */
>>>     qcom,param-override-seq =
>>>             <0x00 0x58>;
>>> ---
>>>  drivers/phy/phy-snps-eusb2.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/phy/phy-snps-eusb2.c b/drivers/phy/phy-snps-eusb2.c
>>> index e232b8b4d29100b8fee9e913e2124788af09f2aa..87fc086424ba4d9fb3ce870aa7f7971a51d4a567 100644
>>> --- a/drivers/phy/phy-snps-eusb2.c
>>> +++ b/drivers/phy/phy-snps-eusb2.c
>>> @@ -420,6 +420,12 @@ static int qcom_snps_eusb2_hsphy_init(struct phy *p)
>>>  	/* set default parameters */
>>>  	qcom_eusb2_default_parameters(phy);
>>>  
>>> +	if (of_device_is_compatible(p->dev.of_node, "qcom,milos-snps-eusb2-phy")) {
>>> +		/* eUSB2 HPG version 1.0.2 update */
>>> +		writel_relaxed(0x0, phy->base + QCOM_USB_PHY_CFG_CTRL_1);
>>> +		readl_relaxed(phy->base + QCOM_USB_PHY_CFG_CTRL_1);
>>
>> Said HPG asks to clear bits [7:1] on all targets
> 
> Okay, so make this unconditional and only update those bits instead of
> writing the full register?

Yes

> 
> Keep the write at this location, or move the code somewhere else in the
> function?
Let's simply do this instead:

diff --git a/drivers/phy/phy-snps-eusb2.c b/drivers/phy/phy-snps-eusb2.c
index 87f323e758d6..6c44d0366f34 100644
--- a/drivers/phy/phy-snps-eusb2.c
+++ b/drivers/phy/phy-snps-eusb2.c
@@ -392,7 +392,7 @@ static int qcom_snps_eusb2_hsphy_init(struct phy *p)
 
        snps_eusb2_hsphy_write_mask(phy->base, QCOM_USB_PHY_CFG_CTRL_1,
                                    PHY_CFG_PLL_CPBIAS_CNTRL_MASK,
-                                   FIELD_PREP(PHY_CFG_PLL_CPBIAS_CNTRL_MASK, 0x1));
+                                   FIELD_PREP(PHY_CFG_PLL_CPBIAS_CNTRL_MASK, 0x0));
 
        snps_eusb2_hsphy_write_mask(phy->base, QCOM_USB_PHY_CFG_CTRL_4,
                                    PHY_CFG_PLL_INT_CNTRL_MASK


Konrad