linux-kernel - [PATCH v3 12/13] mmc: meson-gx: change default tx phase

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Date:   Mon, 28 Aug 2017 16:29:14 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>
Cc:     Jerome Brunet <jbrunet@...libre.com>, linux-mmc@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 12/13] mmc: meson-gx: change default tx phase

Initial default tx phase was set to 0 while the datasheet recommends 270.
Some cards fails to initialize with this setting and eMMC mode DDR52 does
not work.

Changing this setting to 270 fixes these issues, without any regression
so far

Reviewed-by: Kevin Hilman <khilman@...libre.com>
Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
---
 drivers/mmc/host/meson-gx-mmc.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 0cffc705bfe3..efffd36c8d77 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -1156,8 +1156,14 @@ static int meson_mmc_probe(struct platform_device *pdev)
 	if (ret)
 		goto free_host;
 
+	/*
+	 * Set phases : These values are mostly the datasheet recommended ones
+	 * except for the Tx phase. Datasheet recommends 180 but some cards
+	 * fail at initialisation with it. 270 works just fine, it fixes these
+	 * initialisation issues and enable eMMC DDR52 mode.
+	 */
 	host->tp.core_phase = 180;
-	host->tp.tx_phase = 0;
+	host->tp.tx_phase = 270;
 	host->tp.rx_phase = 0;
 
 	ret = meson_mmc_clk_init(host);
-- 
2.9.5