linux-kernel - Re: [PATCH] PCI: mediatek-gen3: Assert resets to ensure expected init state

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Message-ID: <5f61f655-e5bc-9e70-ce11-431b630a5331@collabora.com>
Date:   Tue, 10 May 2022 09:59:22 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     ryder.lee@...iatek.com, jianjun.wang@...iatek.com,
        lorenzo.pieralisi@....com, robh@...nel.org, kw@...ux.com,
        bhelgaas@...gle.com, p.zabel@...gutronix.de,
        matthias.bgg@...il.com, linux-pci@...r.kernel.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kernel@...labora.com,
        nfraprado@...labora.com
Subject: Re: [PATCH] PCI: mediatek-gen3: Assert resets to ensure expected init
 state

Il 09/05/22 19:16, Bjorn Helgaas ha scritto:
> On Mon, May 09, 2022 at 02:18:34PM +0200, AngeloGioacchino Del Regno wrote:
>> Il 04/04/22 16:48, AngeloGioacchino Del Regno ha scritto:
>>> The controller may have been left out of reset by the bootloader,
>>> in which case, before the powerup sequence, the controller will be
>>> found preconfigured with values that were set before booting the
>>> kernel: this produces a controller failure, with the result of
>>> a failure during the mtk_pcie_startup_port() sequence as the PCIe
>>> link never gets up.
>>>
>>> To ensure that we get a clean start in an expected state, assert
>>> both the PHY and MAC resets before executing the controller
>>> power-up sequence.
>>>
>>> Fixes: d3bf75b579b9 ("PCI: mediatek-gen3: Add MediaTek Gen3 driver for MT8192")
>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>>
>> Friendly ping for an important fix :-)
> 
> d3bf75b579b9 appeared in v5.13-rc1 (May 2021, a year ago), so I assume
> this is important for v5.19, but not urgent enough to require being in
> v5.18.  Right?
> 

Hello Bjorn,
no it's not *very* urgent, as MediaTek devices that do require this will be
in v5.19 anyway...

Thanks,
Angelo