From: andy.shevchenko@gmail.com
To: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: agross@kernel.org, andersson@kernel.org,
konrad.dybcio@linaro.org, linus.walleij@linaro.org,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-gpio@vger.kernel.org
Subject: Re: [PATCH v6 1/5] firmware: qcom_scm: provide a read-modify-write function
Date: Sat, 27 May 2023 01:00:48 +0300 [thread overview]
Message-ID: <ZHEsELMsevxAR36x@surfacebook> (raw)
In-Reply-To: <1680076012-10785-2-git-send-email-quic_mojha@quicinc.com>
Wed, Mar 29, 2023 at 01:16:48PM +0530, Mukesh Ojha kirjoitti:
> It was realized by Srinivas K. that there is a need of
> read-modify-write scm exported function so that it can
> be used by multiple clients.
>
> Let's introduce qcom_scm_io_update_field() which masks
> out the bits and write the passed value to that
> bit-offset. Subsequent patch will use this function.
...
> + new = (old & ~mask) | val << (ffs(mask) - 1);
It's a bit non-standard to see left shift here instead of masking.
new = (old & ~mask) | (val & mask);
is usual pattern.
Note as well that your code is prone to subtle mistakes when overflow may
easily override bits outside the mask.
> + return qcom_scm_io_writel(addr, new);
> +}
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2023-05-26 22:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-29 7:46 [PATCH v6 0/5] Refactor to support multiple download mode Mukesh Ojha
2023-03-29 7:46 ` [PATCH v6 1/5] firmware: qcom_scm: provide a read-modify-write function Mukesh Ojha
2023-05-26 22:00 ` andy.shevchenko [this message]
2023-03-29 7:46 ` [PATCH v6 2/5] pinctrl: qcom: Use qcom_scm_io_update_field() Mukesh Ojha
2023-05-26 22:02 ` andy.shevchenko
2023-03-29 7:46 ` [PATCH v6 3/5] firmware: scm: Modify only the download bits in TCSR register Mukesh Ojha
2023-05-26 20:17 ` Bjorn Andersson
2023-03-29 7:46 ` [PATCH v6 4/5] firmware: qcom_scm: Refactor code to support multiple download mode Mukesh Ojha
2023-05-26 22:08 ` andy.shevchenko
2023-06-26 16:27 ` Mukesh Ojha
2023-06-26 17:12 ` Andy Shevchenko
2023-03-29 7:46 ` [PATCH v6 5/5] firmware: qcom_scm: Add multiple download mode support Mukesh Ojha
2023-05-26 22:14 ` andy.shevchenko
2023-05-26 23:36 ` Bjorn Andersson
2023-05-27 7:22 ` Andy Shevchenko
2023-04-10 14:34 ` [PATCH v6 0/5] Refactor to support multiple download mode Mukesh Ojha
2023-05-26 22:15 ` andy.shevchenko
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