linux-kernel - Re: [PATCH 1/1] PCI: Fix Extend ACS configurability

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Message-ID: <20250117132802.GB5556@nvidia.com>
Date: Fri, 17 Jan 2025 09:28:02 -0400
From: Jason Gunthorpe <jgg@...dia.com>
To: Tushar Dave <tdave@...dia.com>
Cc: corbet@....net, bhelgaas@...gle.com, paulmck@...nel.org,
	akpm@...ux-foundation.org, thuth@...hat.com, rostedt@...dmis.org,
	xiongwei.song@...driver.com, vidyas@...dia.com,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, vsethi@...dia.com,
	sdonthineni@...dia.com
Subject: Re: [PATCH 1/1] PCI: Fix Extend ACS configurability

On Thu, Jan 16, 2025 at 05:21:29PM -0800, Tushar Dave wrote:

> -       /* If mask is 0 then we copy the bit from the firmware setting. */
> -       caps->ctrl = (caps->ctrl & ~mask) | (caps->fw_ctrl & mask);
> -       caps->ctrl |= flags;
> +       /* For mask bits that are 0 copy them from the firmware setting
> +        * and apply flags for all the mask bits that are 1.
> +        */
> +       caps->ctrl = (caps->fw_ctrl & ~mask) | (flags & mask);
> 
> 
> I ran some sanity tests and looks good. Can I send V2 now?

I think so, I'm just wondering if this is not quite it either - this
will always throw away any changes any of the other calls made to
ctrl prior to getting here.

So we skip the above if the kernel command line does not refer to the
device?

Ie if the command line refers to the device then it always superceeds
everything, otherwise the other stuff keeps working the way it worked
before??

Jason