From: Jason Cooper <jason@lakedaemon.net>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
linux-pci@vger.kernel.org, patchwork-lst@pengutronix.de,
kernel@pengutronix.de, Bjorn Helgaas <bhelgaas@google.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] PCI: mvebu: change delay after reset to the PCIe spec mandated 100ms
Date: Mon, 16 Jan 2017 11:44:22 +0000 [thread overview]
Message-ID: <20170116114422.GA25924@io.lakedaemon.net> (raw)
In-Reply-To: <20170116111142.6866-1-l.stach@pengutronix.de>
Hi Lucas,
On Mon, Jan 16, 2017 at 12:11:42PM +0100, Lucas Stach wrote:
> The current default of 20ms cause some devices, which are slow to initialize,
> to not show up during the bus scanning. Change this to the PCIe spec mandated
> 100ms and document this in the DT binding.
>
> From PCIe base spec rev 3.0, chapter "6.6.1. Conventional Reset":
>
> "To allow components to perform internal initialization, system software must
> wait a specified minimum period following the end of a Conventional Reset of
> one or more devices before it is permitted to issue Configuration Requests to
> those devices.
>
> With a Downstream Port that does not support Link speeds greater than
> 5.0 GT/s, software must wait a minimum of 100 ms before sending a
> Configuration Request to the device immediately below that Port."
>
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
> Documentation/devicetree/bindings/pci/mvebu-pci.txt | 3 ++-
> drivers/pci/host/pci-mvebu.c | 2 +-
> 2 files changed, 3 insertions(+), 2 deletions(-)
Acked-by: Jason Cooper <jason@lakedaemon.net>
thx,
Jason.
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next prev parent reply other threads:[~2017-01-16 11:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 11:11 [PATCH] PCI: mvebu: change delay after reset to the PCIe spec mandated 100ms Lucas Stach
2017-01-16 11:44 ` Jason Cooper [this message]
2017-01-30 20:47 ` Bjorn Helgaas
2017-01-31 10:27 ` Lucas Stach
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