linux-kernel - [PATCH v4 08/12] mmc: sdhci: Program a relatively accurate SW timeout value

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Message-ID: <20180425120937.29867-9-kishon@ti.com>
Date:   Wed, 25 Apr 2018 17:39:33 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>
CC:     <kishon@...com>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        <linux-mmc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        Tony Lindgren <tony@...mide.com>
Subject: [PATCH v4 08/12] mmc: sdhci: Program a relatively accurate SW timeout value

sdhci has a 10 second timeout to catch devices that stop responding.
In the case of quirk SDHCI_QUIRK2_DISABLE_HW_TIMEOUT, instead of
programming 10 second arbitrary value, calculate the total time it would
take for the entire transfer to happen and program the timeout value
accordingly.

Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 drivers/mmc/host/sdhci.c | 36 ++++++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci.h | 10 ++++++++++
 2 files changed, 46 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index c432ec3644aa..1ed0b8b6570a 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -738,6 +738,39 @@ static unsigned int sdhci_target_timeout(struct sdhci_host *host,
 	return target_timeout;
 }
 
+static void sdhci_calc_sw_timeout(struct sdhci_host *host,
+				  struct mmc_command *cmd)
+{
+	struct mmc_data *data = cmd->data;
+	struct mmc_host *mmc = host->mmc;
+	struct mmc_ios *ios = &mmc->ios;
+	unsigned char bus_width = 1 << ios->bus_width;
+	unsigned int blksz;
+	unsigned int freq;
+	u64 target_timeout;
+	u64 transfer_time;
+
+	target_timeout = sdhci_target_timeout(host, cmd, data);
+	target_timeout *= NSEC_PER_USEC;
+
+	if (data) {
+		blksz = data->blksz;
+		freq = host->mmc->actual_clock ? : host->clock;
+		transfer_time = (u64)blksz * NSEC_PER_SEC * (8 / bus_width);
+		do_div(transfer_time, freq);
+		/* multiply by '2' to account for any unknowns */
+		transfer_time = transfer_time * 2;
+		/* calculate timeout for the entire data */
+		host->data_timeout = data->blocks * target_timeout +
+				     transfer_time;
+	} else {
+		host->data_timeout = target_timeout;
+	}
+
+	if (host->data_timeout)
+		host->data_timeout += MMC_CMD_TRANSFER_TIME;
+}
+
 static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd,
 			     bool *too_big)
 {
@@ -831,6 +864,7 @@ static void sdhci_set_timeout(struct sdhci_host *host, struct mmc_command *cmd)
 
 		if (too_big &&
 		    host->quirks2 & SDHCI_QUIRK2_DISABLE_HW_TIMEOUT) {
+			sdhci_calc_sw_timeout(host, cmd);
 			sdhci_set_data_timeout_irq(host, false);
 		} else if (!(host->ier & SDHCI_INT_DATA_TIMEOUT)) {
 			sdhci_set_data_timeout_irq(host, true);
@@ -845,6 +879,8 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
 	u8 ctrl;
 	struct mmc_data *data = cmd->data;
 
+	host->data_timeout = 0;
+
 	if (sdhci_data_line_cmd(cmd))
 		sdhci_set_timeout(host, cmd);
 
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index f6555c0f4ad3..23966f887da6 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -332,6 +332,14 @@ struct sdhci_adma2_64_desc {
 /* Allow for a a command request and a data request at the same time */
 #define SDHCI_MAX_MRQS		2
 
+/*
+ * 48bit command and 136 bit response in 100KHz clock could take upto 2.48ms.
+ * However since the start time of the command, the time between
+ * command and response, and the time between response and start of data is
+ * not known, set the command transfer time to 10ms.
+ */
+#define MMC_CMD_TRANSFER_TIME	(10 * NSEC_PER_MSEC) /* max 10 ms */
+
 enum sdhci_cookie {
 	COOKIE_UNMAPPED,
 	COOKIE_PRE_MAPPED,	/* mapped by sdhci_pre_req() */
@@ -555,6 +563,8 @@ struct sdhci_host {
 	/* Host SDMA buffer boundary. */
 	u32			sdma_boundary;
 
+	u64			data_timeout;
+
 	unsigned long private[0] ____cacheline_aligned;
 };
 
-- 
2.17.0