Re: [PATCH V1 0/4] GPIO based PCIe Hot-Plug support

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On 10/10/2022 11:44 AM, Vidya Sagar wrote:


On 10/4/2022 9:34 AM, Vidya Sagar wrote:


On 10/3/2022 11:51 PM, Pali Rohár wrote:
External email: Use caution opening links or attachments


On Monday 03 October 2022 13:09:49 Bjorn Helgaas wrote:
On Sat, Oct 01, 2022 at 05:50:07PM -0600, Jonathan Derrick wrote:
On 10/1/2022 10:20 AM, Pali Rohár wrote:
...

Would not it better to rather synthesise PCIe Slot Capabilities support in your PCIe Root Port device (e.g. via pci-bridge-emul.c) and then let
existing PCI hotplug code to take care for hotplugging? Because it
already implements all required stuff for re-scanning, registering and unregistering PCIe devices for Root Ports with Slot Capabilities. And I
think that there is no need to have just another (GPIO based)
implementation of PCI hotplug.

I did that a few years ago (rejected), but can attest to the robustness of
the pcie hotplug code on non-hotplug slots.
https://lwn.net/Articles/811988/

I think the thread is here:
https://lore.kernel.org/linux-pci/1581120007-5280-1-git-send-email-jonathan.derrick@xxxxxxxxx/
and I'm sorry that my response came across as "rejected".  I intended
it as "this is good ideas and good work and we should keep going".

Bjorn

Nice! So we have consensus that this is a good idea. Anyway, if you need
help with designing something here, please let me know as I have good
understanding of all (just two) consumers of pci-bridge-emul.c driver.


Thanks all for your comments.

I would like to hear from Bjorn / Lorenzo if the design of the current patch series is fine at a high level or I should explore emulating the root port's configuration space to fake slot config/control registers (which in turn depend on the hotplug GPIO interrupt & state to update Presence Detect related bits in Slot status register) and use the PCIe native Hot-plug framework itself to carry out with enabling the Hot-plug functionality?

Bjorn / Lorenzo,
Could you please take time to comment on the discussion happened here and the right approach to be followed?

I'm really sorry to bug you on this, but would like to hear your comments on the approach to be taken. So, I would really like to hear your take on this.

Thanks,
Vidya Sagar


Thanks,
Vidya Sagar


Thanks,
Vidya Sagar





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