linux-kernel - Re: [PATCH v2] PCI: endpoint: pci-epf-test: Limit PCIe BAR size for fixed BARs

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Message-ID: <23b3e8e2-ba9d-4cb3-907e-3de7f2693b60@mailbox.org>
Date: Fri, 5 Sep 2025 20:41:53 +0200
From: Marek Vasut <marek.vasut@...lbox.org>
To: Niklas Cassel <cassel@...nel.org>
Cc: linux-pci@...r.kernel.org, Krzysztof Wilczyński
 <kwilczynski@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Damien Le Moal <dlemoal@...nel.org>, Frank Li <Frank.Li@....com>,
 Jerome Brunet <jbrunet@...libre.com>,
 Kishon Vijay Abraham I <kishon@...nel.org>,
 Manivannan Sadhasivam <mani@...nel.org>, Wang Jiang <jiangwang@...inos.cn>,
 linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v2] PCI: endpoint: pci-epf-test: Limit PCIe BAR size for
 fixed BARs

On 9/5/25 2:27 PM, Niklas Cassel wrote:
> On Fri, Sep 05, 2025 at 02:12:43PM +0200, Marek Vasut wrote:
>> Currently, the test allocates BAR sizes according to fixed table
>> bar_size[] = { 512, 512, 1024, 16384, 131072, 1048576 } . This
>> does not work with controllers which have fixed size BARs, like
>> Renesas R-Car V4H PCIe controller, which has BAR4 size limited
>> to 256 Bytes, which is much less than 131072 currently requested
>> by this test.
> 
> Perhaps rephase this to more clearly state that:
> This does not work with controllers with have fixed size BARs that is
> smaller than the requested BAR size.
> 
> (Since a lot of controllers drivers in-tree have fixed size BARs,
> and they do work perfectly fine, but it is only because their fixed
> size is larger than the size requested by pci-epf-test.c)
> 
> 
>>
>> Adjust the test such, that in case a fixed size BAR is detected
>> on a controller, minimum of requested size and fixed size BAR
>> size is used during the test instead.
> 
> This sentence needs to be updated, since you no longer take the minimum
> of requested size and fixed size BAR.
> 
> Perhaps simply:
> "Adjust the test such that in case a fixed size BAR is detected,
> the fixed BAR size is used, as that is the only possibly option."
> 
> 
> With that:
> Reviewed-by: Niklas Cassel <cassel@...nel.org>
All done in V3, which I will send shortly.

Thank you