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References: <20200716141534.30241-1-ulf.hansson@linaro.org>
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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Thu, 16 Jul 2020 20:22:53 +0200
Message-ID: <CAK8P3a1+rwY5uFpUMijgET_W78Tj+tqqKDevgqstjUmmhxdKuA@mail.gmail.com>
Subject: Re: [PATCH] mmc: core: Initial support for SD express card/host
To:     Ulf Hansson <ulf.hansson@linaro.org>
Cc:     linux-mmc <linux-mmc@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Rui Feng <rui_feng@realsil.com.cn>,
        linux-nvme@lists.infradead.org,
        linux-pci <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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On Thu, Jul 16, 2020 at 4:16 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:

> +       /* Continue with the SD express init, if the card supports it. */
> +       resp &= 0x3000;
> +       if (pcie_bits && resp) {
> +               if (resp == 0x3000)
> +                       host->ios.timing = MMC_TIMING_SD_EXP_1_2V;
> +               else
> +                       host->ios.timing = MMC_TIMING_SD_EXP;
> +
> +               /*
> +                * According to the spec the clock shall also be gated, but
> +                * let's leave this to the host driver for more flexibility.
> +                */
> +               return host->ops->init_sd_express(host, &host->ios);
> +       }
> +
>         return 0;
>  }

Does this need an additional handshake or timeout to see if the
device was successfully probed by the nvme driver?

It looks like the card would just disappear here if e.g. the nvme driver
is not loaded or runs into a runtime error.

     Arnd