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Commit 81f8a7be authored by Hans de Goede's avatar Hans de Goede Committed by Ulf Hansson
Browse files

mmc: Add support for marking hpi as broken through devicetree 



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: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent 2391b340

Documentation/devicetree/bindings/mmc/mmc-card.txt

0 → 100644
+31 −0
Original line number Diff line number Diff line 
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 = <&reg_vcc3v3>;

	bus-width = <8>;

	non-removable;

	status = "okay";



	mmccard: mmccard@0 {

		reg = <0>;

		compatible = "mmc-card";

		broken-hpi;

	};

};

drivers/mmc/core/mmc.c

+9 −1
Original line number Diff line number Diff line
@@ -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;