Re: [PATCH v4 06/10] phy: qcom: Add M31 based eUSB2 PHY driver

From: Vinod Koul <vkoul@kernel.org>
To: Wesley Cheng <quic_wcheng@quicinc.com>
Cc: Melody Olvera <melody.olvera@oss.qualcomm.com>,
	Kishon Vijay Abraham I <kishon@kernel.org>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konradybcio@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 06/10] phy: qcom: Add M31 based eUSB2 PHY driver
Date: Wed, 14 May 2025 09:33:44 +0100	[thread overview]
Message-ID: <aCRVaNDQP/PdAXPR@vaman> (raw)
In-Reply-To: <0517c37d-b1ba-466e-bffd-9f47b0d458d5@quicinc.com>

On 16-04-25, 15:45, Wesley Cheng wrote:
> Hi Vinod,
> 
> On 4/10/2025 4:53 AM, Vinod Koul wrote:
> > On 09-04-25, 10:48, Melody Olvera wrote:
> > 
> >> +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);
> > 
> > Why are you using _relaxed version here?
> > 
> 
> No particular reason.  I think someone pointed this out previously, and I
> was open to use the non-relaxed variants, but I assume using the relaxed vs
> non-relaxed apis comes down to preference in this case.

Nope you cant! There _needs_ to be a specific reasons!
When you are doing read, modify, write, it is very important to know the
right version to use...

-- 
~Vinod