linux-kernel - Re: [PATCH] phy: qcom: qmp-combo: Fix VCO div offset on v3

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Message-ID: <f7f7d56a-3292-4641-a479-c0b72d611bc3@quicinc.com>
Date: Thu, 4 Apr 2024 17:02:09 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Stephen Boyd <swboyd@...omium.org>, Vinod Koul <vkoul@...nel.org>,
        Kishon
 Vijay Abraham I <kishon@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <patches@...ts.linux.dev>,
        <linux-arm-msm@...r.kernel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        <linux-phy@...ts.infradead.org>,
        Neil
 Armstrong <neil.armstrong@...aro.org>,
        <freedreno@...ts.freedesktop.org>,
        Douglas Anderson <dianders@...omium.org>,
        Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH] phy: qcom: qmp-combo: Fix VCO div offset on v3



On 4/4/2024 4:43 PM, Stephen Boyd wrote:
> Commit ec17373aebd0 ("phy: qcom: qmp-combo: extract common function to
> setup clocks") changed the offset that is used to write to
> DP_PHY_VCO_DIV from QSERDES_V3_DP_PHY_VCO_DIV to
> QSERDES_V4_DP_PHY_VCO_DIV. Unfortunately, this offset is different
> between v3 and v4 phys:
> 
>   #define QSERDES_V3_DP_PHY_VCO_DIV                 0x064
>   #define QSERDES_V4_DP_PHY_VCO_DIV                 0x070
> 
> meaning that we write the wrong register on v3 phys now. Add another
> generic register to 'regs' and use it here instead of a version specific
> define to fix this.
> 
> This was discovered after Abhinav looked over register dumps with me
> from sc7180 Trogdor devices that started failing to light up the
> external display with v6.6 based kernels. It turns out that some
> monitors are very specific about their link clk frequency and if the
> default power on reset value is still there the monitor will show a
> blank screen or a garbled display. Other monitors are perfectly happy to
> get a bad clock signal.
> 
> Cc: Douglas Anderson <dianders@...omium.org>
> Cc: Abhinav Kumar <quic_abhinavk@...cinc.com>
> Cc: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Fixes: ec17373aebd0 ("phy: qcom: qmp-combo: extract common function to setup clocks")
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> ---
>   drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 

I cross-checked the foll chipsets which use qmp_v3_usb3phy_regs_layout:

-> sdm845
-> sc7180
-> sm6350

All of them have VCO_DIV at offset 0x64.

And, I cross-checked the foll chipsets which use 
qmp_v45_usb3phy_regs_layout:

-> sc8180x
-> x1e80100
-> sm8250
-> sm8350

All of them have VCO_DIV at offset 0x70.

Now, thing look in order to me.

Hence,

Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>