Messages in this thread | | | Date | Mon, 07 Feb 2005 13:47:33 +0900 | From | Tejun Heo <> | Subject | Re: [rfc][patch] ide: fix unneeded LBA48 taskfile registers access |
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Hello, Bartlomiej.
Bartlomiej Zolnierkiewicz wrote: > [ against ide-dev-2.6 tree, boot tested on LBA48 drive ] > > This small patch fixes unneeded writes/reads to LBA48 taskfile registers > on LBA48 capable disks for following cases: > > * Power Management requests > (WIN_FLUSH_CACHE[_EXT], WIN_STANDBYNOW1, WIN_IDLEIMMEDIATE commands) > * special commands (WIN_SPECIFY, WIN_RESTORE, WIN_SETMULT) > * Host Protected Area support (WIN_READ_NATIVE_MAX, WIN_SET_MAX) > * /proc/ide/ SMART support (WIN_SMART with SMART_ENABLE, > SMART_READ_VALUES and SMART_READ_THRESHOLDS subcommands) > * write cache enabling/disabling in ide-disk > (WIN_SETFEATURES with SETFEATURES_{EN,DIS}_WCACHE) > * write cache flushing in ide-disk (WIN_FLUSH_CACHE[_EXT]) > * acoustic management in ide-disk > (WIN_SETFEATURES with SETFEATURES_{EN,DIS}_AAM) > * door (un)locking in ide-disk (WIN_DOORLOCK, WIN_DOORUNLOCK) > * /proc/ide/hd?/identify support (WIN_IDENTIFY) > > Patch adds 'unsinged long flags' to ide_task_t and uses ATA_TFLAG_LBA48 > flag (from <linux/ata.h>) to indicate need of accessing LBA48 taskfile > registers.
ide_task_t already has fields to enable/disable writing/reading of taskfile and hob registers (tf_in_flags and tf_out_flags). How about adding the following two helpers.
static inline ide_init_task[_std](ide_task_t *task) { memset(task, 0, sizeof(*task)); task->tf_out_flags = IDE_TASKFILE_STD_OUT_FLAGS; task->tf_in_flags = IDE_TASKFILE_STD_IN_FLAGS; }
static inline ide_init_task_lba48(ide_task_t *task) { memset(task, 0, sizeof(*task)); task->tf_out_flags = IDE_TASKFILE_STD_OUT_FLAGS | (IDE_HOB_STD_OUT_FLAGS << 8); task->tf_in_flags = IDE_TASKFILE_STD_IN_FLAGS | (IDE_HOB_STD_IN_FLAGS << 8); }
And, when writing taskfile,
if (task->tf_out_flags & 0xf == IDE_TASKFILE_STD_OUT_FLAGS) { /* Write taskfile regs without testing flags */ } else { /* Flagged taskfile */ }
if (task->tf_out_flags & 0xf0 == IDE_TASKFILE_HOB_OUT_FLAGS) { /* Write hob regs without testing flags */ } else { /* Flagged hob */ }
And, when reading taskfile back,
if (task->tf_in_flags & 0xf0) { /* Read all hob regs */ }
/* Read all taskfile regs */
And, we need to check if any of in/out flags is zero in ioctl functions and set STD flags appropriately. So, basically, in kernel, tf_{in|out}_flags == 0 now means 0, not default.
By doing like above,
1. Virtually the same effect 2. No need to add new field to ide_task_t 3. Cleaner semantics (ATA_TFLAG_LBA48 and tf_{in|out}_flags carry duplicate information.)
Thanks.
-- tejun
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