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Commit 70ca826d authored by Gregor Herburger's avatar Gregor Herburger Committed by Greg Kroah-Hartman
Browse files

i2c: ocores: generate stop condition after timeout in polling mode 



[ Upstream commit f8160d3b35fc94491bb0cb974dbda310ef96c0e2 ]

In polling mode, no stop condition is generated after a timeout. This
causes SCL to remain low and thereby block the bus. If this happens
during a transfer it can cause slaves to misinterpret the subsequent
transfer and return wrong values.

To solve this, pass the ETIMEDOUT error up from ocores_process_polling()
instead of setting STATE_ERROR directly. The caller is adjusted to call
ocores_process_timeout() on error both in polling and in IRQ mode, which
will set STATE_ERROR and generate a stop condition.

Fixes: 69c8c0c0 ("i2c: ocores: add polling interface")
Signed-off-by: default avatarGregor Herburger <gregor.herburger@tq-group.com>
Signed-off-by: default avatarMatthias Schiffer <matthias.schiffer@ew.tq-group.com>
Acked-by: default avatarPeter Korsgaard <peter@korsgaard.com>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Reviewed-by: default avatarFederico Vaga <federico.vaga@cern.ch>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 5fb5bdcd

drivers/i2c/busses/i2c-ocores.c

+19 −16
Original line number Diff line number Diff line
@@ -343,18 +343,18 @@ static int ocores_poll_wait(struct ocores_i2c *i2c) 
 * ocores_isr(), we just add our polling code around it.

 *

 * It can run in atomic context

 *

 * Return: 0 on success, -ETIMEDOUT on timeout

 */

static void ocores_process_polling(struct ocores_i2c *i2c)

static int ocores_process_polling(struct ocores_i2c *i2c)

{

	while (1) {

	irqreturn_t ret;

		int err;

	int err = 0;



	while (1) {

		err = ocores_poll_wait(i2c);

		if (err) {

			i2c->state = STATE_ERROR;

		if (err)

			break; /* timeout */

		}



		ret = ocores_isr(-1, i2c);

		if (ret == IRQ_NONE)
@@ -365,13 +365,15 @@ static void ocores_process_polling(struct ocores_i2c *i2c) 
					break;

		}

	}



	return err;

}



static int ocores_xfer_core(struct ocores_i2c *i2c,

			    struct i2c_msg *msgs, int num,

			    bool polling)

{

	int ret;

	int ret = 0;

	u8 ctrl;



	ctrl = oc_getreg(i2c, OCI2C_CONTROL);
@@ -389,15 +391,16 @@ static int ocores_xfer_core(struct ocores_i2c *i2c, 
	oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);



	if (polling) {

		ocores_process_polling(i2c);

		ret = ocores_process_polling(i2c);

	} else {

		ret = wait_event_timeout(i2c->wait,

		if (wait_event_timeout(i2c->wait,

				       (i2c->state == STATE_ERROR) ||

					 (i2c->state == STATE_DONE), HZ);

		if (ret == 0) {

			ocores_process_timeout(i2c);

			return -ETIMEDOUT;

				       (i2c->state == STATE_DONE), HZ) == 0)

			ret = -ETIMEDOUT;

	}

	if (ret) {

		ocores_process_timeout(i2c);

		return ret;

	}



	return (i2c->state == STATE_DONE) ? num : -EIO;