linux-kernel - Re: [PATCH v4 18/18] PCI: j721e: Add suspend and resume support

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: <20240328220751.GA1613553@bhelgaas>
Date: Thu, 28 Mar 2024 17:07:51 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Thomas Richard <thomas.richard@...tlin.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Andy Shevchenko <andy@...nel.org>, Tony Lindgren <tony@...mide.com>,
	Haojian Zhuang <haojian.zhuang@...aro.org>,
	Vignesh R <vigneshr@...com>, Aaro Koskinen <aaro.koskinen@....fi>,
	Janusz Krzysztofik <jmkrzyszt@...il.com>,
	Andi Shyti <andi.shyti@...nel.org>, Peter Rosin <peda@...ntia.se>,
	Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
	linux-i2c@...r.kernel.org, linux-phy@...ts.infradead.org,
	linux-pci@...r.kernel.org, gregory.clement@...tlin.com,
	theo.lebrun@...tlin.com, thomas.petazzoni@...tlin.com,
	u-kumar1@...com
Subject: Re: [PATCH v4 18/18] PCI: j721e: Add suspend and resume support

On Mon, Mar 04, 2024 at 04:36:01PM +0100, Thomas Richard wrote:
> From: Théo Lebrun <theo.lebrun@...tlin.com>
> 
> Add suspend and resume support. Only the rc mode is supported.
> 
> During the suspend stage PERST# is asserted, then deasserted during the
> resume stage.

> +		 * "Power Sequencing and Reset Signal Timings" table in
> +		 * PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 3.0
> +		 * indicates PERST# should be deasserted after minimum of 100us
> +		 * once REFCLK is stable. The REFCLK to the connector in RC
> +		 * mode is selected while enabling the PHY. So deassert PERST#
> +		 * after 100 us.

Please cite current spec (r5.1 was published August 2023), section,
and parameter name.  I think this is T_PERST-CLK, "REFCLK stable
before PERST# inactive", from sec 2.9.2.

> +		 */
> +		if (pcie->reset_gpio) {
> +			fsleep(100);

I'd like to see a macro used here instead of a bare number.  Since
this isn't anything specific to j721e, maybe add something like
#define PCIE_T_PERST_CLK_US alongside PCIE_T_PVPERL_MS.

> +			gpiod_set_value_cansleep(pcie->reset_gpio, 1);
> +		}