linux-kernel - Re: [PATCH v2 1/3] mmc: sdhci-of-arasan: Add DTS property to disable DCMDs.

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Date:   Fri, 8 Mar 2019 14:47:19 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Christoph Muellner <christoph.muellner@...obroma-systems.com>,
        robh+dt@...nel.org, mark.rutland@....com, heiko@...ech.de,
        shawn.lin@...k-chips.com, ulf.hansson@...aro.org
Cc:     Philipp Tomsich <philipp.tomsich@...obroma-systems.com>,
        Michal Simek <michal.simek@...inx.com>,
        Douglas Anderson <dianders@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Lin Huang <hl@...k-chips.com>,
        Tony Xie <tony.xie@...k-chips.com>,
        Randy Li <ayaka@...lik.info>,
        Vicente Bergas <vicencb@...il.com>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Klaus Goger <klaus.goger@...obroma-systems.com>,
        linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v2 1/3] mmc: sdhci-of-arasan: Add DTS property to disable
 DCMDs.

On 7/03/19 10:43 AM, Christoph Muellner wrote:
> Direct commands (DCMDs) are an optional feature of eMMC 5.1's command
> queue engine (CQE). The Arasan eMMC 5.1 controller uses the CQHCI,
> which exposes a control register bit to enable the feature.
> The current implementation sets this bit unconditionally.
> 
> This patch allows to suppress the feature activation,
> by specifying the property disable-cqe-dcmd.
> 
> Signed-off-by: Christoph Muellner <christoph.muellner@...obroma-systems.com>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@...obroma-systems.com>

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  drivers/mmc/host/sdhci-of-arasan.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index c9e3e050ccc8..88dc3f00a5be 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -832,7 +832,10 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
>  		host->mmc_host_ops.start_signal_voltage_switch =
>  					sdhci_arasan_voltage_switch;
>  		sdhci_arasan->has_cqe = true;
> -		host->mmc->caps2 |= MMC_CAP2_CQE | MMC_CAP2_CQE_DCMD;
> +		host->mmc->caps2 |= MMC_CAP2_CQE;
> +
> +		if (!of_property_read_bool(np, "disable-cqe-dcmd"))
> +			host->mmc->caps2 |= MMC_CAP2_CQE_DCMD;
>  	}
>  
>  	ret = sdhci_arasan_add_host(sdhci_arasan);
>