linux-kernel - Re: [PATCH 5/8] tty: mps2-uart: Use devm_clk_get

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

Message-ID: <Zsc645l_nFK_Xp-t@smile.fi.intel.com>
Date: Thu, 22 Aug 2024 16:19:31 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Lei Liu <liulei.rjpt@...o.com>
Cc: Paul Cercueil <paul@...pouillou.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Richard Genoud <richard.genoud@...tlin.com>,
	Nicolas Ferre <nicolas.ferre@...rochip.com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Claudiu Beznea <claudiu.beznea@...on.dev>,
	Liviu Dudau <liviu.dudau@....com>,
	Sudeep Holla <sudeep.holla@....com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Andreas Färber <afaerber@...e.de>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Patrice Chotard <patrice.chotard@...s.st.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	John Ogness <john.ogness@...utronix.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Jeff Johnson <quic_jjohnson@...cinc.com>,
	Valentin Caron <valentin.caron@...s.st.com>,
	Lino Sanfilippo <l.sanfilippo@...bus.com>,
	Amelie Delaunay <amelie.delaunay@...s.st.com>,
	linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org, linux-tegra@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-actions@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	opensource.kernel@...o.com
Subject: Re: [PATCH 5/8] tty: mps2-uart: Use devm_clk_get_enabled() helpers

On Thu, Aug 22, 2024 at 11:39:09AM +0800, Lei Liu wrote:
> The devm_clk_get_enabled() helpers:
>     - call devm_clk_get()
>     - call clk_prepare_enable() and register what is needed in order to
>      call clk_disable_unprepare() when needed, as a managed resource.
> 
> This simplifies the code and avoids calls to clk_disable_unprepare().

...

> -	mps_port->clk = devm_clk_get(&pdev->dev, NULL);
> +	mps_port->clk = devm_clk_get_enabled(&pdev->dev, NULL);
>  	if (IS_ERR(mps_port->clk))
>  		return PTR_ERR(mps_port->clk);
>  
> -	ret = clk_prepare_enable(mps_port->clk);
> -	if (ret)
> -		return ret;
> -
>  	mps_port->port.uartclk = clk_get_rate(mps_port->clk);
>  
> -	clk_disable_unprepare(mps_port->clk);

Your change is not equivalent. In case this clock is shared this may lead to
run-time issues. Hence I don't think this patch is needed in this case.
Instead, you may add a comment on top of devm_clk_get() to explain that we only
need it be enabled to get clock rate in the probe.

-- 
With Best Regards,
Andy Shevchenko