Discussion:
ufs: add UFS power management support
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Dan Carpenter
2014-10-02 15:31:12 UTC
Permalink
Hello Subhash Jadavani,

The patch 57d104c153d3: "ufs: add UFS power management support" from
Sep 25, 2014, leads to the following static checker warning:

drivers/scsi/ufs/ufshcd.c:4746 ufshcd_link_state_transition()
warn: we tested 'check_for_bkops' before and it was 'true'

drivers/scsi/ufs/ufshcd.c
4734 if (req_link_state == UIC_LINK_HIBERN8_STATE) {
4735 ret = ufshcd_uic_hibern8_enter(hba);
4736 if (!ret)
4737 ufshcd_set_link_hibern8(hba);
4738 else
4739 goto out;
4740 }
4741 /*
4742 * If autobkops is enabled, link can't be turned off because
4743 * turning off the link would also turn off the device.
4744 */
4745 else if ((req_link_state == UIC_LINK_OFF_STATE) &&
4746 (!check_for_bkops || (check_for_bkops &&
^^^^^^^^^^^^^^^
Not needed.

4747 !hba->auto_bkops_enabled))) {
4748 /*
4749 * Change controller state to "reset state" which
4750 * should also put the link in off/reset state
4751 */
4752 ufshcd_hba_stop(hba);
4753 /*
4754 * TODO: Check if we need any delay to make sure that
4755 * controller is reset
4756 */
4757 ufshcd_set_link_off(hba);
4758 }
4759
4760 out:
4761 return ret;
4762 }

regards,
dan carpenter
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Dolev Raviv
2014-10-23 07:28:52 UTC
Permalink
Hi Dan,
This seem like a false alarm, please let me know if it requires a fix.

Thanks,
Dolev
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-----Original Message-----
From: Dan Carpenter [mailto:***@oracle.com]
Sent: Thursday, October 02, 2014 6:31 PM
To: ***@codeaurora.org
Cc: linux-***@vger.kernel.org
Subject: re: ufs: add UFS power management support

Hello Subhash Jadavani,

The patch 57d104c153d3: "ufs: add UFS power management support" from Sep 25,
2014, leads to the following static checker warning:

drivers/scsi/ufs/ufshcd.c:4746 ufshcd_link_state_transition()
warn: we tested 'check_for_bkops' before and it was 'true'

drivers/scsi/ufs/ufshcd.c
4734 if (req_link_state == UIC_LINK_HIBERN8_STATE) {
4735 ret = ufshcd_uic_hibern8_enter(hba);
4736 if (!ret)
4737 ufshcd_set_link_hibern8(hba);
4738 else
4739 goto out;
4740 }
4741 /*
4742 * If autobkops is enabled, link can't be turned off because
4743 * turning off the link would also turn off the device.
4744 */
4745 else if ((req_link_state == UIC_LINK_OFF_STATE) &&
4746 (!check_for_bkops || (check_for_bkops &&
^^^^^^^^^^^^^^^ Not needed.

4747 !hba->auto_bkops_enabled))) {
4748 /*
4749 * Change controller state to "reset state" which
4750 * should also put the link in off/reset state
4751 */
4752 ufshcd_hba_stop(hba);
4753 /*
4754 * TODO: Check if we need any delay to make sure
that
4755 * controller is reset
4756 */
4757 ufshcd_set_link_off(hba);
4758 }
4759
4760 out:
4761 return ret;
4762 }

regards,
dan carpenter

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Dan Carpenter
2014-10-23 10:06:30 UTC
Permalink
Post by Dolev Raviv
Hi Dan,
This seem like a false alarm, please let me know if it requires a fix.
It may not indicate a bug, but it is correct in that the code could be
re-written:

Old:

else if ((req_link_state == UIC_LINK_OFF_STATE) &&
(!check_for_bkops || (check_for_bkops &&
!hba->auto_bkops_enabled))) {

Proposed:

else if ((req_link_state == UIC_LINK_OFF_STATE) &&
(!check_for_bkops || !hba->auto_bkops_enabled)) {

Those two are the same.

regards,
dan carpenter


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