linux-kernel - Re: [PATCH] PCI: apple: Reset the port for 100ms on probe

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Message-ID: <87lf1l7nf3.wl-maz@kernel.org>
Date:   Thu, 18 Nov 2021 10:45:04 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Pali Rohár <pali@...nel.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org,
        kernel-team@...roid.com, Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH] PCI: apple: Reset the port for 100ms on probe

On Thu, 18 Nov 2021 10:01:58 +0000,
Marc Zyngier <maz@...nel.org> wrote:
> 
> There is also a third delay (Tperst-clk) which represents the time
> required for the clock to ramp up before releasing #PERST. No, there
> is no value associated with this.

Actually, there is. At least the PCIe CMS r2.0 (2.6.2. AC
Specifications) does provide a table of the timings. Tperst-clk has a
minimum value of 100us.

Which means I can tighten things further.

	M.

-- 
Without deviation from the norm, progress is not possible.