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From:   Christoph Muellner <christoph.muellner@theobroma-systems.com>
To:     robh+dt@kernel.org, mark.rutland@arm.com, heiko@sntech.de,
        shawn.lin@rock-chips.com, ulf.hansson@linaro.org,
        adrian.hunter@intel.com
Cc:     Christoph Muellner <christoph.muellner@theobroma-systems.com>,
        Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
        Michal Simek <michal.simek@xilinx.com>,
        Douglas Anderson <dianders@chromium.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Jeffy Chen <jeffy.chen@rock-chips.com>,
        Shunqian Zheng <zhengsq@rock-chips.com>,
        Ezequiel Garcia <ezequiel@collabora.com>,
        Randy Li <ayaka@soulik.info>,
        Tony Xie <tony.xie@rock-chips.com>,
        Vicente Bergas <vicencb@gmail.com>,
        Klaus Goger <klaus.goger@theobroma-systems.com>,
        linux-mmc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org
Subject: [PATCH 1/3] dt-bindings: mmc: Add DTS property to disable DCMDs on Arasan controllers
Date:   Fri,  1 Mar 2019 17:43:45 +0100
Message-Id: <20190301164349.60589-1-christoph.muellner@theobroma-systems.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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 surpress the feature activation,
by specifying the property disable-cqe-dcmd.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.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);
-- 
2.11.0