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bd: Tweaked block device API to fit SD cards and FTLs better #4983

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Merged
merged 3 commits into from
Sep 21, 2017
Merged

bd: Tweaked block device API to fit SD cards and FTLs better #4983

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e798c53
bd: Changed BlockDevice erase to default as no-op
geky Aug 28, 2017
6e1b9e1
bd: Added trim function to let filesystems give erase hints to FTLs
geky Aug 28, 2017
ee88097
fatfs: Adopted the trim function in the FAT filesystem
geky Aug 28, 2017
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26 changes: 24 additions & 2 deletions features/filesystem/bd/BlockDevice.h
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Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,26 @@ class BlockDevice
* @param size Size to erase in bytes, must be a multiple of erase block size
* @return 0 on success, negative error code on failure
*/
virtual int erase(bd_addr_t addr, bd_size_t size) = 0;
virtual int erase(bd_addr_t addr, bd_size_t size)
{
return 0;
}

/** Mark blocks as no longer in use
*
* This function provides a hint to the underlying block device that a region of blocks
* is no longer in use and may be erased without side effects. Erase must still be called
* before programming, but trimming allows flash-translation-layers to schedule erases when
* the device is not busy.
*
* @param addr Address of block to mark as unused
* @param size Size to mark as unused in bytes, must be a multiple of erase block size
* @return 0 on success, negative error code on failure
*/
virtual int trim(bd_addr_t addr, bd_size_t size)
{
return 0;
}

/** Get the size of a readable block
*
Expand All @@ -111,7 +130,10 @@ class BlockDevice
* @return Size of a eraseable block in bytes
* @note Must be a multiple of the program size
*/
virtual bd_size_t get_erase_size() const = 0;
virtual bd_size_t get_erase_size() const
{
return get_program_size();
}

/** Get the total size of the underlying device
*
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2 changes: 1 addition & 1 deletion features/filesystem/fat/ChaN/ffconf.h
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Expand Up @@ -171,7 +171,7 @@
/ disk_ioctl() function. */


#define _USE_TRIM 0
#define _USE_TRIM 1
/* This option switches ATA-TRIM feature. (0:Disable or 1:Enable)
/ To enable Trim feature, also CTRL_TRIM command should be implemented to the
/ disk_ioctl() function. */
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9 changes: 9 additions & 0 deletions features/filesystem/fat/FATFileSystem.cpp
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Expand Up @@ -244,6 +244,15 @@ DRESULT disk_ioctl(BYTE pdrv, BYTE cmd, void *buff)
case GET_BLOCK_SIZE:
*((DWORD*)buff) = 1; // default when not known
return RES_OK;
case CTRL_TRIM:
if (_ffs[pdrv] == NULL) {
return RES_NOTRDY;
} else {
DWORD *sectors = (DWORD*)buff;
DWORD ssize = disk_get_sector_size(pdrv);
int err = _ffs[pdrv]->trim(sectors[0]*ssize, (sectors[1]-sectors[0]+1)*ssize);
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Arguments to erase function were start sector, and total size to erase. Please clarify what are the arguments of trim? sectors[0] / sectors[1] what do they contain?

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Ah sure: http://elm-chan.org/fsw/ff/doc/dioctl.html

The sector block is specified by a DWORD array {<start sector>, <end sector>}

So sectors[0] is the start sector, and sectors[1] is the end sector (inclusive) of the trim operation.

return err ? RES_PARERR : RES_OK;
}
}

return RES_PARERR;
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