linux-kernel - RE: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up

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Date:   Tue, 26 Oct 2021 09:18:39 +0000
From:   Richard Zhu <hongxing.zhu@....com>
To:     Francesco Dolcini <francesco.dolcini@...adex.com>
CC:     Mark Brown <broonie@...nel.org>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "jingoohan1@...il.com" <jingoohan1@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: RE: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never
 came up

Snipped...

> > >
> > > Hello Richard,
> > > I have one curiosity on this topic. Does this works well in case the
> > > regulator is shared? I just want to be sure that if the regulator is
> > > shared everything is working fine even if the PCI-E link is not used or not
> coming up for any reason.
> > >
> > [Richard Zhu] Hi Francesco:
> > Actually, this regulator used by i.MX PCIe controller driver is one fixed gpio
> regulator.
> > Refer to my understand, this regulator is not shared by different devices.
> >
> > Up to now, it works fine to power up the PCIe slot populated on the HW
> board.
> 
> Isn't this something that depend on the actual board design? From the driver
> point of view you should not silently enforce such design requirement on the
> board.
> Am I missing something here? Would be glad to you if you can clarify in case.
> 
[Richard Zhu] Yes, it is relied on the actual HW board design.
This regulator is one optional, not mandatory required for all the board designs.
So, there is one _enabled or not check before manipulate this regulator.

BR
Richard

> Francesco
>