The eMMC on a tablet I've will stop working / communicating as soon as
the kernel executes:
mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
EXT_CSD_HPI_MGMT, 1,
card->ext_csd.generic_cmd6_time);
There seems to be no way to reliable identify eMMC-s which have a broken
hpi implementation, but at least for eMMC's which are soldered onto a board
we can work around this by specifying that hpi is broken in devicetree.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Changes in v2:
-Fix of_node leakage
---
Documentation/devicetree/bindings/mmc/mmc-card.txt | 31 ++++++++++++++++++++++
drivers/mmc/core/mmc.c | 10 ++++++-
2 files changed, 40 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/mmc/mmc-card.txt
diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.txt b/Documentation/devicetree/bindings/mmc/mmc-card.txt
new file mode 100644
index 0000000..a70fcd6
--- /dev/null
+++ b/Documentation/devicetree/bindings/mmc/mmc-card.txt
@@ -0,0 +1,31 @@
+mmc-card / eMMC bindings
+------------------------
+
+This documents describes the devicetree bindings for a mmc-host controller
+child node describing a mmc-card / an eMMC, see "Use of Function subnodes"
+in mmc.txt
+
+Required properties:
+-compatible : Must be "mmc-card"
+-reg : Must be <0>
+
+Optional properties:
+-broken-hpi : Use this to indicate that the mmc-card has a broken hpi
+ implementation, and that hpi should not be used
+
+Example:
+
+&mmc2 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&mmc2_pins_a>;
+ vmmc-supply = <®_vcc3v3>;
+ bus-width = <8>;
+ non-removable;
+ status = "okay";
+
+ mmccard: mmccard@0 {
+ reg = <0>;
+ compatible = "mmc-card";
+ broken-hpi;
+ };
+};
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 1d41e85..c84131e 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -11,6 +11,7 @@
*/
#include <linux/err.h>
+#include <linux/of.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/pm_runtime.h>
@@ -336,6 +337,8 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
{
int err = 0, idx;
unsigned int part_size;
+ struct device_node *np;
+ bool broken_hpi = false;
/* Version is coded in the CSD_STRUCTURE byte in the EXT_CSD register */
card->ext_csd.raw_ext_csd_structure = ext_csd[EXT_CSD_STRUCTURE];
@@ -349,6 +352,11 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
}
}
+ np = mmc_of_find_child_device(card->host, 0);
+ if (np && of_device_is_compatible(np, "mmc-card"))
+ broken_hpi = of_property_read_bool(np, "broken-hpi");
+ of_node_put(np);
+
/*
* The EXT_CSD format is meant to be forward compatible. As long
* as CSD_STRUCTURE does not change, all values for EXT_CSD_REV
@@ -494,7 +502,7 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
}
/* check whether the eMMC card supports HPI */
- if (ext_csd[EXT_CSD_HPI_FEATURES] & 0x1) {
+ if (!broken_hpi && (ext_csd[EXT_CSD_HPI_FEATURES] & 0x1)) {
card->ext_csd.hpi = 1;
if (ext_csd[EXT_CSD_HPI_FEATURES] & 0x2)
card->ext_csd.hpi_cmd = MMC_STOP_TRANSMISSION;
--
2.3.4
--
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