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Enhanced the FAT32 filesystem code to understand DMA preflight failures, and to use the file sector buffer as a bounce buffer when a user-supplied buffer is not suitable for DMA. From Mike Smith

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This commit is contained in:
Gregory Nutt 2013-10-18 08:38:44 -06:00
parent 6a524b5734
commit f479f5d698
2 changed files with 83 additions and 36 deletions
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4
ChangeLog
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@ -5806,3 +5806,7 @@
* drivers/mmcsd/mmscd_sdio.c: Enhanced the mmcdd_sdio driver to perform
DMA preflight operations and fail DMA read/write requests that fail
preflighting. From Mike Smith (2013-10-18).
* fs/fat/fs_fat32.c: Enhanced the FAT32 filesystem code to understand DMA
preflight failures, and to use the file sector buffer as a bounce buffer
when a user-supplied buffer is not suitable for DMA. From Mike Smith
(2013-10-18).

115
fs/fat/fs_fat32.c
View File

@ -265,7 +265,7 @@ static int fat_open(FAR struct file *filep, const char *relpath,
* directory path was found, but the file was not found in the
* final directory.
*/
else if (ret == -ENOENT)
{
/* The file does not exist. Were we asked to create it? */
@ -287,7 +287,7 @@ static int fat_open(FAR struct file *filep, const char *relpath,
}
/* Fall through to finish the file open operation */
direntry = &fs->fs_buffer[dirinfo.fd_seq.ds_offset];
}
@ -355,7 +355,7 @@ static int fat_open(FAR struct file *filep, const char *relpath,
fs->fs_head = ff->ff_next;
fat_semgive(fs);
/* In write/append mode, we need to set the file pointer to the end of the file */
if ((oflags & (O_APPEND|O_WRONLY)) == (O_APPEND|O_WRONLY))
@ -447,6 +447,7 @@ static ssize_t fat_read(FAR struct file *filep, char *buffer, size_t buflen)
uint8_t *userbuffer = (uint8_t*)buffer;
int sectorindex;
int ret;
bool force_indirect = false;
/* Sanity checks */
@ -517,13 +518,15 @@ static ssize_t fat_read(FAR struct file *filep, char *buffer, size_t buflen)
{
bytesread = 0;
fat_read_restart:
/* Check if the user has provided a buffer large enough to
* hold one or more complete sectors -AND- the read is
* aligned to a sector boundary.
*/
nsectors = buflen / fs->fs_hwsectorsize;
if (nsectors > 0 && sectorindex == 0)
if (nsectors > 0 && sectorindex == 0 && !force_indirect)
{
/* Read maximum contiguous sectors directly to the user's
* buffer without using our tiny read buffer.
@ -549,6 +552,22 @@ static ssize_t fat_read(FAR struct file *filep, char *buffer, size_t buflen)
ret = fat_hwread(fs, userbuffer, ff->ff_currentsector, nsectors);
if (ret < 0)
{
#ifdef CONFIG_FAT_DMAMEMORY
/* The low-level driver may return -EFAULT in the case where
* the transfer cannot be performed due to DMA constraints.
* It is probable that the buffer is completely un-DMA-able,
* so force indirect transfers via the sector buffer and
* restart the operation.
*/
if (ret == -EFAULT)
{
fdbg("DMA: read alignment error, restarting indirect\n");
force_indirect = true;
goto fat_read_restart;
}
#endif
goto errout_with_semaphore;
}
@ -558,7 +577,8 @@ static ssize_t fat_read(FAR struct file *filep, char *buffer, size_t buflen)
}
else
{
/* We are reading a partial sector. First, read the whole sector
/* We are reading a partial sector, or handling a non-DMA-able
* whole-sector transfer. First, read the whole sector
* into the file data buffer. This is a caching buffer so if
* it is already there then all is well.
*/
@ -569,7 +589,7 @@ static ssize_t fat_read(FAR struct file *filep, char *buffer, size_t buflen)
goto errout_with_semaphore;
}
/* Copy the partial sector into the user buffer */
/* Copy the requested part of the sector into the user buffer */
bytesread = fs->fs_hwsectorsize - sectorindex;
if (bytesread > buflen)
@ -645,6 +665,7 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
uint8_t *userbuffer = (uint8_t*)buffer;
int sectorindex;
int ret;
bool force_indirect = false;
/* Sanity checks. I have seen the following assertion misfire if
* CONFIG_DEBUG_MM is enabled while re-directing output to a
@ -735,8 +756,10 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
* hold one or more complete sectors.
*/
fat_write_restart:
nsectors = buflen / fs->fs_hwsectorsize;
if (nsectors > 0 && sectorindex == 0)
if (nsectors > 0 && sectorindex == 0 && !force_indirect)
{
/* Write maximum contiguous sectors directly from the user's
* buffer without using our tiny read buffer.
@ -763,6 +786,22 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
ret = fat_hwwrite(fs, userbuffer, ff->ff_currentsector, nsectors);
if (ret < 0)
{
#ifdef CONFIG_FAT_DMAMEMORY
/* The low-level driver may return -EFAULT in the case where
* the transfer cannot be performed due to DMA constraints.
* It is probable that the buffer is completely un-DMA-able,
* so force indirect transfers via the sector buffer and
* restart the operation.
*/
if (ret == -EFAULT)
{
fdbg("DMA: write alignment error, restarting indirect\n");
force_indirect = true;
goto fat_write_restart;
}
#endif
goto errout_with_semaphore;
}
@ -773,30 +812,22 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
}
else
{
/* We are writing a partial sector -OR- the current sector
* has not yet been filled.
/* Decide whether we are performing a read-modify-write
* operation, in which case we have to read the existing sector
* into the buffer first.
*
* We will first have to read the full sector in memory as
* part of a read-modify-write operation. NOTE we don't
* have to read the data on a rare case: When we are extending
* the file (filep->f_pos == ff->ff_size) -AND- the new data
* happens to be aligned at the beginning of the sector
* (sectorindex == 0).
* There are two cases where we can avoid this read:
*
* - If we are performing a whole-sector write that was rejected
* by fat_hwwrite(), i.e. sectorindex == 0 and buflen >= sector size.
*
* - If the write is aligned to the beginning of the sector and
* extends beyond the end of the file, i.e. sectorindex == 0 and
* file pos + buflen >= file size.
*/
if (filep->f_pos < ff->ff_size || sectorindex != 0)
{
/* Read the current sector into memory (perhaps first flushing
* the old, dirty sector to disk).
*/
ret = fat_ffcacheread(fs, ff, ff->ff_currentsector);
if (ret < 0)
{
goto errout_with_semaphore;
}
}
else
if ((sectorindex == 0) && ((buflen >= fs->fs_hwsectorsize) ||
((filep->f_pos + buflen) >= ff->ff_size)))
{
/* Flush unwritten data in the sector cache. */
@ -810,15 +841,27 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
ff->ff_cachesector = ff->ff_currentsector;
}
else
{
/* Read the current sector into memory (perhaps first flushing
* the old, dirty sector to disk).
*/
/* Copy the partial sector from the user buffer */
ret = fat_ffcacheread(fs, ff, ff->ff_currentsector);
if (ret < 0)
{
goto errout_with_semaphore;
}
}
/* Copy the requested part of the sector from the user buffer */
writesize = fs->fs_hwsectorsize - sectorindex;
if (writesize > buflen)
{
/* We will not write to the end of the buffer. Set
* write size to the size of the user buffer.
*/
/* We will not write to the end of the buffer. Set
* write size to the size of the user buffer.
*/
writesize = buflen;
}
@ -1445,7 +1488,7 @@ static int fat_opendir(struct inode *mountpt, const char *relpath, struct fs_dir
{
/* The entry is a directory (but not the root directory) */
dir->u.fat.fd_startcluster =
dir->u.fat.fd_startcluster =
((uint32_t)DIR_GETFSTCLUSTHI(direntry) << 16) |
DIR_GETFSTCLUSTLO(direntry);
dir->u.fat.fd_currcluster = dir->u.fat.fd_startcluster;
@ -1499,7 +1542,7 @@ static int fat_readdir(struct inode *mountpt, struct fs_dirent_s *dir)
dir->fd_dir.d_name[0] = '\0';
found = false;
while (dir->u.fat.fd_currsector && !found)
{
ret = fat_fscacheread(fs, dir->u.fat.fd_currsector);
@ -2012,7 +2055,7 @@ static int fat_mkdir(struct inode *mountpt, const char *relpath, mode_t mode)
goto errout_with_semaphore;
}
/* Flush any existing, dirty data in fs_buffer (because we need
/* Flush any existing, dirty data in fs_buffer (because we need
* it to create the directory entries.
*/
@ -2294,7 +2337,7 @@ int fat_rename(struct inode *mountpt, const char *oldrelpath,
{
goto errout_with_semaphore;
}
/* Write the old entry to disk and update FSINFO if necessary */
ret = fat_updatefsinfo(fs);