From: Niklas Cassel <cassel@kernel.org>
To: Koichiro Den <den@valinux.co.jp>
Cc: "Marek Vasut" <marek.vasut+renesas@gmail.com>,
"Yoshihiro Shimoda" <yoshihiro.shimoda.uh@renesas.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
"Manivannan Sadhasivam" <mani@kernel.org>,
"Rob Herring" <robh@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Geert Uytterhoeven" <geert+renesas@glider.be>,
"Magnus Damm" <magnus.damm@gmail.com>,
linux-pci@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] PCI: dwc: rcar-gen4: Use 4K EPC BAR alignment
Date: Thu, 5 Mar 2026 08:37:35 +0100 [thread overview]
Message-ID: <aakyvxxFnBkl4io5@ryzen> (raw)
In-Reply-To: <20260305015439.1529006-1-den@valinux.co.jp>
On Thu, Mar 05, 2026 at 10:54:39AM +0900, Koichiro Den wrote:
> R-Car S4 Series (R8A779F[4-7]*) uses a 4K minimum iATU region size
> (CX_ATU_MIN_REGION_SIZE = 4K) as per R19UH0161EJ0130 Rev.1.30.
>
> Update the advertised alignment to 4K, as described in
> commit 2a9a801620ef ("PCI: endpoint: Add support to specify alignment
> for buffers allocated to BARs").
>
> With the previous 1MB alignment requirement, iATU programming for BAR4
> on this platform often cannot be performed, since a 1MB-aligned target
> address may fall outside the tiny 256B BAR4 window.
You could also mention that CX_ATU_MIN_REGION_SIZE can configured to
a value in range 4 kB to 64 kB, so 1 MB is clearly bogus.
Reviewed-by: Niklas Cassel <cassel@kernel.org>
next prev parent reply other threads:[~2026-03-05 7:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-05 1:54 [PATCH] PCI: dwc: rcar-gen4: Use 4K EPC BAR alignment Koichiro Den
2026-03-05 5:57 ` Manivannan Sadhasivam
2026-03-05 7:03 ` Koichiro Den
2026-03-05 8:14 ` Manivannan Sadhasivam
2026-03-05 14:15 ` Koichiro Den
2026-03-05 7:34 ` Niklas Cassel
2026-03-05 7:37 ` Niklas Cassel [this message]
2026-03-05 14:13 ` Koichiro Den
2026-03-05 15:46 ` Niklas Cassel
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