nvme/scsi: Remove power management support

As far as I can tell, there is basically nothing correct about this
code.  It misinterprets npss (off-by-one).  It hardcodes a bunch of
power states, which is nonsense, because they're all just indices
into a table that software needs to parse.  It completely ignores
the distinction between operational and non-operational states.
And, until 4.8, if all of the above magically succeeded, it would
dereference a NULL pointer and OOPS.

Since this code appears to be useless, just delete it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jay Freyensee <james_p_freyensee@linux.intel.com>
Tested-by: Jay Freyensee <james_p_freyensee@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 3 insertions, 71 deletions

diff --git a/drivers/nvme/host/scsi.c b/drivers/nvme/host/scsi.c
index e947e298a737..44009105f8c8 100644
--- a/drivers/nvme/host/scsi.c
+++ b/drivers/nvme/host/scsi.c
@@ -72,15 +72,6 @@ static int sg_version_num = 30534;	/* 2 digits for each component */
 #define ALL_LUNS_RETURNED                               0x02
 #define ALL_WELL_KNOWN_LUNS_RETURNED                    0x01
 #define RESTRICTED_LUNS_RETURNED                        0x00
-#define NVME_POWER_STATE_START_VALID                    0x00
-#define NVME_POWER_STATE_ACTIVE                         0x01
-#define NVME_POWER_STATE_IDLE                           0x02
-#define NVME_POWER_STATE_STANDBY                        0x03
-#define NVME_POWER_STATE_LU_CONTROL                     0x07
-#define POWER_STATE_0                                   0
-#define POWER_STATE_1                                   1
-#define POWER_STATE_2                                   2
-#define POWER_STATE_3                                   3
 #define DOWNLOAD_SAVE_ACTIVATE                          0x05
 #define DOWNLOAD_SAVE_DEFER_ACTIVATE                    0x0E
 #define ACTIVATE_DEFERRED_MICROCODE                     0x0F
@@ -1229,64 +1220,6 @@ static void nvme_trans_fill_read_cap(u8 *response, struct nvme_id_ns *id_ns,
 
 /* Start Stop Unit Helper Functions */
 
-static int nvme_trans_power_state(struct nvme_ns *ns, struct sg_io_hdr *hdr,
-                                                u8 pc, u8 pcmod, u8 start)
-{
-        int res;
-        int nvme_sc;
-        struct nvme_id_ctrl *id_ctrl;
-        int lowest_pow_st;      /* max npss = lowest power consumption */
-        unsigned ps_desired = 0;
-
-        nvme_sc = nvme_identify_ctrl(ns->ctrl, &id_ctrl);
-        res = nvme_trans_status_code(hdr, nvme_sc);
-        if (res)
-                return res;
-
-        lowest_pow_st = max(POWER_STATE_0, (int)(id_ctrl->npss - 1));
-        kfree(id_ctrl);
-
-        switch (pc) {
-        case NVME_POWER_STATE_START_VALID:
-                /* Action unspecified if POWER CONDITION MODIFIER != 0 */
-                if (pcmod == 0 && start == 0x1)
-                        ps_desired = POWER_STATE_0;
-                if (pcmod == 0 && start == 0x0)
-                        ps_desired = lowest_pow_st;
-                break;
-        case NVME_POWER_STATE_ACTIVE:
-                /* Action unspecified if POWER CONDITION MODIFIER != 0 */
-                if (pcmod == 0)
-                        ps_desired = POWER_STATE_0;
-                break;
-        case NVME_POWER_STATE_IDLE:
-                /* Action unspecified if POWER CONDITION MODIFIER != [0,1,2] */
-                if (pcmod == 0x0)
-                        ps_desired = POWER_STATE_1;
-                else if (pcmod == 0x1)
-                        ps_desired = POWER_STATE_2;
-                else if (pcmod == 0x2)
-                        ps_desired = POWER_STATE_3;
-                break;
-        case NVME_POWER_STATE_STANDBY:
-                /* Action unspecified if POWER CONDITION MODIFIER != [0,1] */
-                if (pcmod == 0x0)
-                        ps_desired = max(POWER_STATE_0, (lowest_pow_st - 2));
-                else if (pcmod == 0x1)
-                        ps_desired = max(POWER_STATE_0, (lowest_pow_st - 1));
-                break;
-        case NVME_POWER_STATE_LU_CONTROL:
-        default:
-                res = nvme_trans_completion(hdr, SAM_STAT_CHECK_CONDITION,
-                                ILLEGAL_REQUEST, SCSI_ASC_INVALID_CDB,
-                                SCSI_ASCQ_CAUSE_NOT_REPORTABLE);
-                break;
-        }
-        nvme_sc = nvme_set_features(ns->ctrl, NVME_FEAT_POWER_MGMT, ps_desired, 0,
-                                    NULL);
-        return nvme_trans_status_code(hdr, nvme_sc);
-}
-
 static int nvme_trans_send_activate_fw_cmd(struct nvme_ns *ns, struct sg_io_hdr *hdr,
                                         u8 buffer_id)
 {
@@ -2235,11 +2168,10 @@ static int nvme_trans_synchronize_cache(struct nvme_ns *ns,
 static int nvme_trans_start_stop(struct nvme_ns *ns, struct sg_io_hdr *hdr,
                                                         u8 *cmd)
 {
-        u8 immed, pcmod, pc, no_flush, start;
+        u8 immed, pcmod, no_flush, start;
 
         immed = cmd[1] & 0x01;
         pcmod = cmd[3] & 0x0f;
-        pc = (cmd[4] & 0xf0) >> 4;
         no_flush = cmd[4] & 0x04;
         start = cmd[4] & 0x01;
 
@@ -2254,8 +2186,8 @@ static int nvme_trans_start_stop(struct nvme_ns *ns, struct sg_io_hdr *hdr,
                         if (res)
                                 return res;
                 }
-                /* Setup the expected power state transition */
-                return nvme_trans_power_state(ns, hdr, pc, pcmod, start);
+
+                return 0;
         }
 }