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Commit 6b73da50 authored by Sujit Reddy Thumma's avatar Sujit Reddy Thumma
Browse files

scsi: ufs: retry if the link-startup fails 



In some cases, due to hardware timing issues the Uni-Pro link-startup
might fail. The UFS HCI recovery procedure contradicts the Uni-Pro
sequence. The UFS HCI specifies to resend DME_LINKSTARTUP command
after IS.ULLS (link-lost interrupt) is received. The Uni-Pro specifies
that if link-startup fails the link is in "down" state. The link-lost is
indicated to the DME user only when the link is up. Hence, the UFS HCI
recovery procedure of waiting for IS.ULLS and retrying link-startup may
not work properly.

In order to resolve the ambiguity, reset the host controller to make
sure the link is in down state and retry the link-startup.

Change-Id: I6b2c97d341a6b4e78c1d6245fe9bd32db26a2a89
Signed-off-by: default avatarSujit Reddy Thumma <sthumma@codeaurora.org>
parent ad0ce55e

drivers/scsi/ufs/ufshcd.c

+26 −10
Original line number Diff line number Diff line
@@ -80,6 +80,9 @@ 
/* Task management command timeout */

#define TM_CMD_TIMEOUT	100 /* msecs */



/* maximum number of link-startup retries */

#define DME_LINKSTARTUP_RETRIES 3



/* Expose the flag value from utp_upiu_query.value */

#define MASK_QUERY_UPIU_FLAG_LOC 0xFF
@@ -1977,21 +1980,34 @@ static int ufshcd_hba_enable(struct ufs_hba *hba) 
static int ufshcd_link_startup(struct ufs_hba *hba)

{

	int ret;

	int retries = DME_LINKSTARTUP_RETRIES;



	do {

		if (hba->vops && hba->vops->link_startup_notify)

			hba->vops->link_startup_notify(hba, PRE_CHANGE);



		ret = ufshcd_dme_link_startup(hba);

	if (ret)

		goto out;



		/* check if device is detected by inter-connect layer */

	if (!ufshcd_is_device_present(hba)) {

		if (!ret && !ufshcd_is_device_present(hba)) {

			dev_err(hba->dev, "%s: Device not present\n", __func__);

			ret = -ENXIO;

			goto out;

		}



		/*

		 * DME link lost indication is only received when link is up,

		 * but we can't be sure if the link is up until link startup

		 * succeeds. So reset the local Uni-Pro and try again.

		 */

		if (ret && ufshcd_hba_enable(hba))

			goto out;

	} while (ret && retries--);



	if (ret)

		/* failed to get the link up... retire */

		goto out;



	/* Include any host controller configuration via UIC commands */

	if (hba->vops && hba->vops->link_startup_notify) {

		ret = hba->vops->link_startup_notify(hba, POST_CHANGE);