From: Zach Brown <zach.brown@ni.com>
To: ulf.hansson@linaro.org
Cc: adrian.hunter@intel.com, robh+dt@kernel.org,
mark.rutland@arm.com, linux-mmc@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
zach.brown@ni.com
Subject: [RFC v2 2/2] sdhci: Prevent SD from doing high-speed timing when broken-highspeed property is set
Date: Wed, 12 Oct 2016 13:40:56 -0500 [thread overview]
Message-ID: <1476297656-7019-3-git-send-email-zach.brown@ni.com> (raw)
In-Reply-To: <1476297656-7019-1-git-send-email-zach.brown@ni.com>
When the broken-highspeed property is set the sdhci driver will not
go into highspeed mode even if the controller and card appear to
otherwise support highspeed mode.
This is useful in cases where the controller and card support highspeed,
but the board configuration or some other issue make highspeed
impossible. For example, we send the SDIO lines through a fpga so we
need the data to change on the falling edge of the clock or there will
be issues with hold time.
Signed-off-by: Zach Brown <zach.brown@ni.com>
---
drivers/mmc/host/sdhci.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 4805566..17e6c50 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -22,6 +22,7 @@
#include <linux/scatterlist.h>
#include <linux/regulator/consumer.h>
#include <linux/pm_runtime.h>
+#include <linux/of.h>
#include <linux/leds.h>
@@ -3274,7 +3275,8 @@ int sdhci_setup_host(struct sdhci_host *host)
if (host->quirks2 & SDHCI_QUIRK2_HOST_NO_CMD23)
mmc->caps &= ~MMC_CAP_CMD23;
- if (host->caps & SDHCI_CAN_DO_HISPD)
+ if ((host->caps & SDHCI_CAN_DO_HISPD) &&
+ !(of_property_read_bool(mmc_dev(mmc)->of_node, "broken-highspeed")))
mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED;
if ((host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) &&
--
2.7.4
next prev parent reply other threads:[~2016-10-12 18:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-12 18:40 [RFC v2 0/2] Add device tree property and driver behavior for supporting sdhci configurations with broken highspeed Zach Brown
[not found] ` <1476297656-7019-1-git-send-email-zach.brown-acOepvfBmUk@public.gmane.org>
2016-10-12 18:40 ` [RFC v2 1/2] sdhci: Add device tree property broken-highspeed Zach Brown
2016-10-13 2:27 ` Jaehoon Chung
[not found] ` <1476297656-7019-2-git-send-email-zach.brown-acOepvfBmUk@public.gmane.org>
2016-10-18 13:17 ` Rob Herring
2016-10-12 18:40 ` Zach Brown [this message]
2016-10-17 6:56 ` [RFC v2 2/2] sdhci: Prevent SD from doing high-speed timing when broken-highspeed property is set Adrian Hunter
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