linux-kernel - Re: [Patch V5 2/3] tpm_tis-spi: Support hardware wait polling

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Message-ID: <Y/9W+7fiRRMqw5LB@sirena.org.uk>
Date:   Wed, 1 Mar 2023 13:45:31 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     Krishna Yarlagadda <kyarlagadda@...dia.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "peterhuewe@....de" <peterhuewe@....de>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Sowjanya Komatineni <skomatineni@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>
Subject: Re: [Patch V5 2/3] tpm_tis-spi: Support hardware wait polling

On Wed, Mar 01, 2023 at 09:39:28AM -0400, Jason Gunthorpe wrote:
> On Wed, Mar 01, 2023 at 12:37:27PM +0000, Mark Brown wrote:

> > It's not like these buses are hot pluggable - someone would have to
> > design and manufacture a board which doesn't work.  It's probably
> > reasonable for this to fail with the SPI subsystem saying it can't
> > support things when the operation is tried.

> If the spi subsystem fails this request with these flags that would be
> great, it would cause the TPM to fail probing reliably.

> But does this patch do that? It looks like non-supporting half duplex
> drivers will just ignore the new flag?

That's something we can fix up in SPI, we shouldn't worry about it for
the client drivers.

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