linux-kernel - [PATCH v3 1/2] mmc: host: dw_mmc: support setting f

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Message-Id: <20220305215835.2210388-2-pgwipeout@gmail.com>
Date:   Sat,  5 Mar 2022 16:58:34 -0500
From:   Peter Geis <pgwipeout@...il.com>
To:     Jaehoon Chung <jh80.chung@...sung.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     robin.murphy@....com, linux-rockchip@...ts.infradead.org,
        Peter Geis <pgwipeout@...il.com>, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/2] mmc: host: dw_mmc: support setting f_min from host drivers

Host drivers may not be able to support frequencies as low as dw-mmc
supports. Unfortunately f_min isn't available when the drv_data->init
function is called, as the mmc_host struct hasn't been set up yet.

Support the host drivers saving the requested minimum frequency, so we
can later set f_min when it is available.

Signed-off-by: Peter Geis <pgwipeout@...il.com>
---
 drivers/mmc/host/dw_mmc.c | 7 ++++++-
 drivers/mmc/host/dw_mmc.h | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 42bf8a2287ba..0d90d0201759 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2898,7 +2898,12 @@ static int dw_mci_init_slot_caps(struct dw_mci_slot *slot)
 	if (host->pdata->caps2)
 		mmc->caps2 = host->pdata->caps2;
 
-	mmc->f_min = DW_MCI_FREQ_MIN;
+	/* if host has set a minimum_freq, we should respect it */
+	if (host->minimum_speed)
+		mmc->f_min = host->minimum_speed;
+	else
+		mmc->f_min = DW_MCI_FREQ_MIN;
+
 	if (!mmc->f_max)
 		mmc->f_max = DW_MCI_FREQ_MAX;
 
diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
index 7f1e38621d13..4ed81f94f7ca 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h
@@ -99,6 +99,7 @@ struct dw_mci_dma_slave {
  * @bus_hz: The rate of @mck in Hz. This forms the basis for MMC bus
  *	rate and timeout calculations.
  * @current_speed: Configured rate of the controller.
+ * @minimum_speed: Stored minimum rate of the controller.
  * @fifoth_val: The value of FIFOTH register.
  * @verid: Denote Version ID.
  * @dev: Device associated with the MMC controller.
@@ -201,6 +202,7 @@ struct dw_mci {
 
 	u32			bus_hz;
 	u32			current_speed;
+	u32			minimum_speed;
 	u32			fifoth_val;
 	u16			verid;
 	struct device		*dev;
-- 
2.25.1