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From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Logan Gunthorpe <logang@deltatee.com>, linux-pci@vger.kernel.org
Subject: Re: [PATCH] PCI: Add sysfs attribute for disabling PCIe link to downstream component
Date: Wed, 3 Jul 2019 15:30:36 +0300	[thread overview]
Message-ID: <20190703123036.GT2640@lahna.fi.intel.com> (raw)
In-Reply-To: <20190529104942.74991-1-mika.westerberg@linux.intel.com>

On Wed, May 29, 2019 at 01:49:42PM +0300, Mika Westerberg wrote:
> PCIe root and downstream ports have link control register that can be
> used disable the link from software. This can be useful for instance
> when performing "software" hotplug on systems that do not support real
> PCIe/ACPI hotplug.
> 
> For example when used with FPGA card we can burn a new FPGA image
> without need to reboot the system.
> 
> First we remove the FGPA device from Linux PCI stack:
> 
>   # echo 1 > /sys/bus/pci/devices/0000:00:01.1/0000:02:00.0/remove
> 
> Then we disable the link:
> 
>   # echo 1 > /sys/bus/pci/devices/0000:00:01.1/link_disable
> 
> By doing this we prevent the kernel from accessing the hardware while we
> burn the new FPGA image. Once the new FPGA is burned we can re-enable
> the link and rescan the new and possibly different device:
> 
>   # echo 0 > /sys/bus/pci/devices/0000:00:01.1/link_disable
>   # echo 1 > /sys/bus/pci/devices/0000:00:01.1/rescan
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Hi,

Any comments on this?

  reply	other threads:[~2019-07-03 12:30 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-29 10:49 [PATCH] PCI: Add sysfs attribute for disabling PCIe link to downstream component Mika Westerberg
2019-07-03 12:30 ` Mika Westerberg [this message]
2019-07-03 13:39 ` Bjorn Helgaas
2019-07-03 15:03   ` Mika Westerberg
2019-08-01 21:53     ` Bjorn Helgaas
2019-08-04 11:51       ` Wu Hao
2019-08-06 10:12       ` Mika Westerberg
2019-08-19 23:52         ` Bjorn Helgaas
2019-08-20  9:58           ` Mika Westerberg
2019-08-20 14:17             ` Bjorn Helgaas
2019-08-21  7:28               ` Mika Westerberg
2019-08-21 14:37                 ` Mika Westerberg
2019-08-21 19:01                   ` Bjorn Helgaas

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