ide-tape remove pipeline speed/control calculations

Pipeline handling calculations in idetape_calculate_speeds() can
go since they do not have any effect on other functionality besides:

1. info is only being exported through /proc as a read-only item
(controlled_pipeline_head_speed, uncontrolled_pipeline_head_speed)

2. used in idetape_restart_speed_control() which, in turn, is unrelated to
other code

3. used only for pipeline frames number accounting (tape->pipeline_head),
also unused elsewhere.

4.some variables are:
        only written to: tape->buffer_head;
        unused: tape->tape_head, tape->last_tape_head

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 71ebee0..e785145 100644 (file)
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -84,9 +84,6 @@ enum {
  * We start from MIN maximum stages (we will not even use MIN stages if we don't
  * need them), increment it by RATE*(MAX-MIN) whenever we sense that the
  * pipeline is empty, until we reach the optimum value or until we reach MAX.
- *
- * Setting the following parameter to 0 is illegal: the pipelined mode cannot be
- * disabled (idetape_calculate_speeds() divides by tape->max_stages.)
  */
 #define IDETAPE_MIN_PIPELINE_STAGES      1
 #define IDETAPE_MAX_PIPELINE_STAGES    400
@@ -392,39 +389,12 @@ typedef struct ide_tape_obj {
         */
        int postpone_cnt;
 
-       /*
-        * Measures number of frames:
-        *
-        * 1. written/read to/from the driver pipeline (pipeline_head).
-        * 2. written/read to/from the tape buffers (idetape_bh).
-        * 3. written/read by the tape to/from the media (tape_head).
-        */
-       int pipeline_head;
-       int buffer_head;
-       int tape_head;
-       int last_tape_head;
-
        /* Speed control at the tape buffers input/output */
        unsigned long insert_time;
        int insert_size;
        int insert_speed;
-       int max_insert_speed;
        int measure_insert_time;
 
-       /* Speed regulation negative feedback loop */
-       int speed_control;
-       int pipeline_head_speed;
-       int controlled_pipeline_head_speed;
-       int uncontrolled_pipeline_head_speed;
-       int controlled_last_pipeline_head;
-       unsigned long uncontrolled_pipeline_head_time;
-       unsigned long controlled_pipeline_head_time;
-       int controlled_previous_pipeline_head;
-       int uncontrolled_previous_pipeline_head;
-       unsigned long controlled_previous_head_time;
-       unsigned long uncontrolled_previous_head_time;
-       int restart_speed_control_req;
-
        u32 debug_mask;
 } idetape_tape_t;
 
@@ -1333,69 +1303,6 @@ static void idetape_create_mode_sense_cmd(struct ide_atapi_pc *pc, u8 page_code)
        pc->idetape_callback = &idetape_pc_callback;
 }
 
-static void idetape_calculate_speeds(ide_drive_t *drive)
-{
-       idetape_tape_t *tape = drive->driver_data;
-
-       if (time_after(jiffies,
-                       tape->controlled_pipeline_head_time + 120 * HZ)) {
-               tape->controlled_previous_pipeline_head =
-                       tape->controlled_last_pipeline_head;
-               tape->controlled_previous_head_time =
-                       tape->controlled_pipeline_head_time;
-               tape->controlled_last_pipeline_head = tape->pipeline_head;
-               tape->controlled_pipeline_head_time = jiffies;
-       }
-       if (time_after(jiffies, tape->controlled_pipeline_head_time + 60 * HZ))
-               tape->controlled_pipeline_head_speed = (tape->pipeline_head -
-                               tape->controlled_last_pipeline_head) * 32 * HZ /
-                               (jiffies - tape->controlled_pipeline_head_time);
-       else if (time_after(jiffies, tape->controlled_previous_head_time))
-               tape->controlled_pipeline_head_speed = (tape->pipeline_head -
-                               tape->controlled_previous_pipeline_head) * 32 *
-                       HZ / (jiffies - tape->controlled_previous_head_time);
-
-       if (tape->nr_pending_stages < tape->max_stages/*- 1 */) {
-               /* -1 for read mode error recovery */
-               if (time_after(jiffies, tape->uncontrolled_previous_head_time +
-                                       10 * HZ)) {
-                       tape->uncontrolled_pipeline_head_time = jiffies;
-                       tape->uncontrolled_pipeline_head_speed =
-                               (tape->pipeline_head -
-                                tape->uncontrolled_previous_pipeline_head) *
-                               32 * HZ / (jiffies -
-                                       tape->uncontrolled_previous_head_time);
-               }
-       } else {
-               tape->uncontrolled_previous_head_time = jiffies;
-               tape->uncontrolled_previous_pipeline_head = tape->pipeline_head;
-               if (time_after(jiffies, tape->uncontrolled_pipeline_head_time +
-                                       30 * HZ))
-                       tape->uncontrolled_pipeline_head_time = jiffies;
-
-       }
-       tape->pipeline_head_speed = max(tape->uncontrolled_pipeline_head_speed,
-                                       tape->controlled_pipeline_head_speed);
-
-       if (tape->speed_control == 1) {
-               if (tape->nr_pending_stages >= tape->max_stages / 2)
-                       tape->max_insert_speed = tape->pipeline_head_speed +
-                               (1100 - tape->pipeline_head_speed) * 2 *
-                               (tape->nr_pending_stages - tape->max_stages / 2)
-                               / tape->max_stages;
-               else
-                       tape->max_insert_speed = 500 +
-                               (tape->pipeline_head_speed - 500) * 2 *
-                               tape->nr_pending_stages / tape->max_stages;
-
-               if (tape->nr_pending_stages >= tape->max_stages * 99 / 100)
-                       tape->max_insert_speed = 5000;
-       } else
-               tape->max_insert_speed = tape->speed_control;
-
-       tape->max_insert_speed = max(tape->max_insert_speed, 500);
-}
-
 static ide_startstop_t idetape_media_access_finished(ide_drive_t *drive)
 {
        idetape_tape_t *tape = drive->driver_data;
@@ -1548,7 +1455,6 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
        if (time_after(jiffies, tape->insert_time))
                tape->insert_speed = tape->insert_size / 1024 * HZ /
                                        (jiffies - tape->insert_time);
-       idetape_calculate_speeds(drive);
        if (!test_and_clear_bit(IDETAPE_FLAG_IGNORE_DSC, &tape->flags) &&
            (stat & SEEK_STAT) == 0) {
                if (postponed_rq == NULL) {
@@ -1572,7 +1478,6 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
                return ide_stopped;
        }
        if (rq->cmd[0] & REQ_IDETAPE_READ) {
-               tape->buffer_head++;
                tape->postpone_cnt = 0;
                pc = idetape_next_pc_storage(drive);
                idetape_create_read_cmd(tape, pc, rq->current_nr_sectors,
@@ -1580,7 +1485,6 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
                goto out;
        }
        if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
-               tape->buffer_head++;
                tape->postpone_cnt = 0;
                pc = idetape_next_pc_storage(drive);
                idetape_create_write_cmd(tape, pc, rq->current_nr_sectors,
@@ -2321,24 +2225,6 @@ static void idetape_empty_write_pipeline(ide_drive_t *drive)
        }
 }
 
-static void idetape_restart_speed_control(ide_drive_t *drive)
-{
-       idetape_tape_t *tape = drive->driver_data;
-
-       tape->restart_speed_control_req = 0;
-       tape->pipeline_head = 0;
-       tape->controlled_last_pipeline_head = 0;
-       tape->controlled_previous_pipeline_head = 0;
-       tape->uncontrolled_previous_pipeline_head = 0;
-       tape->controlled_pipeline_head_speed = 5000;
-       tape->pipeline_head_speed = 5000;
-       tape->uncontrolled_pipeline_head_speed = 0;
-       tape->controlled_pipeline_head_time =
-               tape->uncontrolled_pipeline_head_time = jiffies;
-       tape->controlled_previous_head_time =
-               tape->uncontrolled_previous_head_time = jiffies;
-}
-
 static int idetape_init_read(ide_drive_t *drive, int max_stages)
 {
        idetape_tape_t *tape = drive->driver_data;
@@ -2381,8 +2267,6 @@ static int idetape_init_read(ide_drive_t *drive, int max_stages)
                        }
                }
        }
-       if (tape->restart_speed_control_req)
-               idetape_restart_speed_control(drive);
        idetape_init_rq(&rq, REQ_IDETAPE_READ);
        rq.sector = tape->first_frame;
        rq.nr_sectors = blocks;
@@ -2451,8 +2335,6 @@ static int idetape_add_chrdev_read_request(ide_drive_t *drive, int blocks)
                spin_lock_irqsave(&tape->lock, flags);
                idetape_remove_stage_head(drive);
                spin_unlock_irqrestore(&tape->lock, flags);
-               tape->pipeline_head++;
-               idetape_calculate_speeds(drive);
        }
        if (bytes_read > blocks * tape->blk_size) {
                printk(KERN_ERR "ide-tape: bug: trying to return more bytes"
@@ -2787,8 +2669,6 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
        }
        if (count == 0)
                return (0);
-       if (tape->restart_speed_control_req)
-               idetape_restart_speed_control(drive);
        if (tape->merge_stage_size) {
                if (tape->merge_stage_size >= tape->stage_size) {
                        printk(KERN_ERR "ide-tape: bug: merge buf too big\n");
@@ -2997,7 +2877,6 @@ static int idetape_chrdev_ioctl(struct inode *inode, struct file *file,
 
        debug_log(DBG_CHRDEV, "Enter %s, cmd=%u\n", __func__, cmd);
 
-       tape->restart_speed_control_req = 1;
        if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
                idetape_empty_write_pipeline(drive);
                idetape_flush_tape_buffers(drive);
@@ -3140,8 +3019,6 @@ static int idetape_chrdev_open(struct inode *inode, struct file *filp)
                        }
                }
        }
-       idetape_restart_speed_control(drive);
-       tape->restart_speed_control_req = 0;
        return 0;
 
 out_put_tape:
@@ -3344,12 +3221,6 @@ static void idetape_add_settings(ide_drive_t *drive)
                        NULL);
        ide_add_setting(drive, "dsc_overlap", SETTING_RW, TYPE_BYTE, 0, 1, 1,
                        1, &drive->dsc_overlap, NULL);
-       ide_add_setting(drive, "pipeline_head_speed_c", SETTING_READ, TYPE_INT,
-                       0, 0xffff, 1, 1, &tape->controlled_pipeline_head_speed,
-                       NULL);
-       ide_add_setting(drive, "pipeline_head_speed_u", SETTING_READ, TYPE_INT,
-                       0, 0xffff, 1, 1,
-                       &tape->uncontrolled_pipeline_head_speed, NULL);
        ide_add_setting(drive, "avg_speed", SETTING_READ, TYPE_INT, 0, 0xffff,
                        1, 1, &tape->avg_speed, NULL);
        ide_add_setting(drive, "debug_mask", SETTING_RW, TYPE_INT, 0, 0xffff, 1,
@@ -3395,8 +3266,6 @@ static void idetape_setup(ide_drive_t *drive, idetape_tape_t *tape, int minor)
        tape->name[2] = '0' + minor;
        tape->chrdev_dir = IDETAPE_DIR_NONE;
        tape->pc = tape->pc_stack;
-       tape->max_insert_speed = 10000;
-       tape->speed_control = 1;
        *((unsigned short *) &gcw) = drive->id->config;
 
        /* Command packet DRQ type */