mmc: tifm_sd: Inform the mmc core about the maximum busy timeout

Some commands uses R1B responses, which means the card may assert the DAT0
line to signal busy for a period of time, after it has received the
command. The mmc core normally specifies the busy period for the command in
the cmd->busy_timeout. Ideally the driver should respect it, but that
requires quite some update of the code, so let's defer that to someone with
the HW at hand.

Instead, let's inform the mmc core about the maximum supported busy timeout
in ->max_busy_timeout during ->probe(). This value corresponds to the fixed
1s timeout used by tifm_sd. In this way, we let the mmc core validate the
needed timeout, which may lead to that it converts from a R1B into a R1
response and then use CMD13 to poll for busy completion.

In other words, this change enables support for commands with longer busy
periods than 1s, like erase (CMD38) for example.

Cc: Alex Dubov <oakad@yahoo.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20200414161413.3036-16-ulf.hansson@linaro.org

drivers/mmc/host/tifm_sd.c

@@ -73,6 +73,8 @@ module_param(fixed_timeout, bool, 0644);
 
 #define TIFM_MMCSD_MAX_BLOCK_SIZE  0x0800UL
 
+#define TIFM_MMCSD_REQ_TIMEOUT_MS  1000
+
 enum {
 	CMD_READY    = 0x0001,
 	FIFO_READY   = 0x0002,
@@ -959,7 +961,12 @@ static int tifm_sd_probe(struct tifm_dev *sock)
 	host = mmc_priv(mmc);
 	tifm_set_drvdata(sock, mmc);
 	host->dev = sock;
-	host->timeout_jiffies = msecs_to_jiffies(1000);
+	host->timeout_jiffies = msecs_to_jiffies(TIFM_MMCSD_REQ_TIMEOUT_MS);
+	/*
+	 * We use a fixed request timeout of 1s, hence inform the core about it.
+	 * A future improvement should instead respect the cmd->busy_timeout.
+	 */
+	mmc->max_busy_timeout = TIFM_MMCSD_REQ_TIMEOUT_MS;
 
 	tasklet_init(&host->finish_tasklet, tifm_sd_end_cmd,
 		     (unsigned long)host);