mmc: sdhci: specify maximum discard timeout

In general, SDHC hardware timeout cannot be avoided.
Accordingly, the maximum timeout is specified to limit
the maximum discard size.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -2509,6 +2509,11 @@ int sdhci_add_host(struct sdhci_host *host)
 	} else
 		mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_200;
 
+	if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
+		mmc->max_discard_to = (1 << 27) / (mmc->f_max / 1000);
+	else
+		mmc->max_discard_to = (1 << 27) / host->timeout_clk;
+
 	mmc->caps |= MMC_CAP_SDIO_IRQ | MMC_CAP_ERASE | MMC_CAP_CMD23;
 
 	if (host->quirks & SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12)