From: Bjorn Helgaas <helgaas@kernel.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: "Lorenzo Bianconi" <lorenzo@kernel.org>,
"Ryder Lee" <ryder.lee@mediatek.com>,
"Jianjun Wang" <jianjun.wang@mediatek.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Rob Herring" <robh@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Matthias Brugger" <matthias.bgg@gmail.com>,
"Christian Marangi" <ansuelsmth@gmail.com>,
linux-pci@vger.kernel.org, linux-mediatek@lists.infradead.org,
linux-arm-kernel@lists.infradead.org, upstream@airoha.com,
"Hui Ma" <hui.ma@airoha.com>
Subject: Re: [PATCH] PCI: mediatek-gen3: Avoid PCIe resetting for Airoha EN7581 SoC
Date: Mon, 30 Sep 2024 14:37:56 -0500 [thread overview]
Message-ID: <20240930193756.GA187798@bhelgaas> (raw)
In-Reply-To: <d8941149-9125-4fe2-a1c0-ab29223a0c87@collabora.com>
On Mon, Sep 23, 2024 at 11:41:41AM +0200, AngeloGioacchino Del Regno wrote:
> Il 20/09/24 10:26, Lorenzo Bianconi ha scritto:
> > The PCIe controller available on the EN7581 SoC does not support reset
> > via the following lines:
> > - PCIE_MAC_RSTB
> > - PCIE_PHY_RSTB
> > - PCIE_BRG_RSTB
> > - PCIE_PE_RSTB
> >
> > Introduce the reset callback in order to avoid resetting the PCIe port
> > for Airoha EN7581 SoC.
>
> EN7581 doesn't support pulling up/down PERST#?! That looks
> definitely odd, as that signal is part of the PCI-Express CEM spec.
>
> Besides, there's another PERST# assertion at
> mtk_pcie_suspend_noirq()...
I agree, it doesn't smell right that this SoC doesn't have a way to
assert PERST#.
The response at
https://lore.kernel.org/r/SG2PR03MB63415DB5791C58C7EA69FF01FF682@SG2PR03MB6341.apcprd03.prod.outlook.com
suggests that maybe there's a hardware defect that means asserting
PERST# doesn't work correctly? But surely firmware must have a way of
asserting PERST#, at least at boot time.
If this is truly a hardware defect and we really can't assert PERST#,
please say that this is a defect in the commit log so people don't
think that lack of PERST# is an acceptable thing.
Bjorn
next prev parent reply other threads:[~2024-09-30 19:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-20 8:26 [PATCH] PCI: mediatek-gen3: Avoid PCIe resetting for Airoha EN7581 SoC Lorenzo Bianconi
2024-09-23 9:41 ` AngeloGioacchino Del Regno
[not found] ` <SG2PR03MB6341D9B41B5742BD45E09B46FF6F2@SG2PR03MB6341.apcprd03.prod.outlook.com>
2024-09-23 11:28 ` 回复: " AngeloGioacchino Del Regno
2024-09-24 6:53 ` 回复: " Hui Ma (马慧)
2024-09-30 19:37 ` Bjorn Helgaas [this message]
2024-10-01 17:15 ` Lorenzo Bianconi
2024-10-08 10:38 ` 回复: " Hui Ma (马慧)
2024-09-23 17:10 ` Bjorn Helgaas
2024-09-23 21:29 ` Lorenzo Bianconi
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