linux-kernel - Re: [PATCH v5 06/10] phy: qcom: Add M31 based eUSB2 PHY driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <423565b7-6b11-40bc-accf-902e80314300@oss.qualcomm.com>
Date: Thu, 22 May 2025 17:09:27 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Song Xue <quic_songxue@...cinc.com>,
        Melody Olvera <melody.olvera@....qualcomm.com>,
        Vinod Koul
 <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Wesley Cheng <quic_wcheng@...cinc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Subject: Re: [PATCH v5 06/10] phy: qcom: Add M31 based eUSB2 PHY driver

On 5/22/25 12:56 PM, Song Xue wrote:
> 
> 
> On 4/22/2025 6:00 AM, Melody Olvera wrote:
>> From: Wesley Cheng <quic_wcheng@...cinc.com>
>>
>> SM8750 utilizes an eUSB2 PHY from M31.  Add the initialization
>> sequences to bring it out of reset and into an operational state.  This
>> differs to the M31 USB driver, in that the M31 eUSB2 driver will
>> require a connection to an eUSB2 repeater.  This PHY driver will handle
>> the initialization of the associated eUSB2 repeater when required.
>>
>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
>> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
>> Signed-off-by: Melody Olvera <melody.olvera@....qualcomm.com>
>> ---

[...]

>> +static int m31eusb2_phy_write_readback(void __iomem *base, u32 offset,
>> +                    const u32 mask, u32 val)
>> +{
>> +    u32 write_val;
>> +    u32 tmp;
>> +
>> +    tmp = readl_relaxed(base + offset);
>> +    tmp &= ~mask;
>> +    write_val = tmp | val;
>> +
>> +    writel_relaxed(write_val, base + offset);
>> +
>> +    tmp = readl_relaxed(base + offset);
> is it better to use "readl" which can guarantee write visibility?

let's use non-relaxed to save the meaningless discussion from dragging
on, in fight for what is literally a couple nanoseconds each boot

Konrad