linux.git/drivers/mmc/card/queue.h, branch master

mmc: block: Move files to core

2016-12-12T15:30:05+00:00

Once upon a time it made sense to keep the mmc block device driver and its
related code, in its own directory called card. Over time, more an more
functions/structures have become shared through generic mmc header files,
between the core and the card directory. In other words, the relationship
between them has become closer.

By sharing functions/structures via generic header files, it becomes easy
for outside users to abuse them. In a way to avoid that from happen, let's
move the files from card directory into the core directory, as it enables
us to move definitions of functions/structures into mmc core specific
header files.

Note, this is only the first step in providing a cleaner mmc interface for
outside users. Following changes will do the actual cleanup, as that is not
part of this change.

Signed-off-by: Ulf Hansson 
Reviewed-by: Linus Walleij

mmc: queue: Introduce queue depth and use it to allocate and free

2016-12-05T09:31:07+00:00

Add a mmc_queue member to record the size of the queue, which currently
supports 2 requests on-the-go at a time. Instead of allocating resources
for 2 slots in the queue, allow for an arbitrary number.

Signed-off-by: Adrian Hunter 
Signed-off-by: Ulf Hansson

mmc: queue: Fix queue thread wake-up

2016-12-05T09:31:03+00:00

The only time the driver sleeps expecting to be woken upon the arrival of
a new request, is when the dispatch queue is empty. The only time that it
is known whether the dispatch queue is empty is after NULL is returned
from blk_fetch_request() while under the queue lock.

Recognizing those facts, simplify the synchronization between the queue
thread and the request function. A couple of flags tell the request
function what to do, and the queue lock and barriers associated with
wake-ups ensure synchronization.

The result is simpler and allows the removal of the context_info lock.

Signed-off-by: Adrian Hunter 
Reviewed-by: Linus Walleij 
Reviewed-by: Harjani Ritesh 
Signed-off-by: Ulf Hansson

mmc: block: delete packed command support

2016-11-29T08:05:27+00:00

I've had it with this code now.

The packed command support is a complex hurdle in the MMC/SD block
layer, around 500+ lines of code which was introduced in 2013 in

commit ce39f9d17c14 ("mmc: support packed write command for eMMC4.5
devices")
commit abd9ac144947 ("mmc: add packed command feature of eMMC4.5")

...and since then it has been rotting. The original author of the
code has disappeared from the community and the mail address is
bouncing.

For the code to be exercised the host must flag that it supports
packed commands, so in mmc_blk_prep_packed_list() which is called for
every single request, the following construction appears:

u8 max_packed_rw = 0;

if ((rq_data_dir(cur) == WRITE) &&
    mmc_host_packed_wr(card->host))
        max_packed_rw = card->ext_csd.max_packed_writes;

if (max_packed_rw == 0)
    goto no_packed;

This has the following logical deductions:

- Only WRITE commands can really be packed, so the solution is
  only half-done: we support packed WRITE but not packed READ.
  The packed command support has not been finalized by supporting
  reads in three years!

- mmc_host_packed_wr() is just a static inline that checks
  host->caps2 & MMC_CAP2_PACKED_WR. The problem with this is
  that NO upstream host sets this capability flag! No driver
  in the kernel is using it, and we can't test it. Packed
  command may be supported in out-of-tree code, but I doubt
  it. I doubt that the code is even working anymore due to
  other refactorings in the MMC block layer, who would
  notice if patches affecting it broke packed commands?
  No one.

- There is no Device Tree binding or code to mark a host as
  supporting packed read or write commands, just this flag
  in caps2, so for sure there are not any DT systems using
  it either.

It has other problems as well: mmc_blk_prep_packed_list() is
speculatively picking requests out of the request queue with
blk_fetch_request() making the MMC/SD stack harder to convert
to the multiqueue block layer. By this we get rid of an
obstacle.

The way I see it this is just cruft littering the MMC/SD
stack.

Cc: Namjae Jeon 
Cc: Maya Erez 
Acked-by: Jaehoon Chung 
Signed-off-by: Linus Walleij 
Signed-off-by: Ulf Hansson

mmc: block: move packed command struct init

2016-11-29T08:05:04+00:00

By moving the mmc_packed_init() and mmc_packed_clean() into the
only file in the kernel where they are used, we save two exported
functions and can staticize those to the block.c file.

Signed-off-by: Linus Walleij 
Signed-off-by: Ulf Hansson

mmc: block: rename data to blkdata

2016-11-29T08:05:04+00:00

The struct mmc_blk_request contains an opaque void *data that
is actually only used to store a pointer to a per-request
struct mmc_blk_data. This is confusing, so rename the member
to blkdata and forward-declare the block.c local struct.

Signed-off-by: Linus Walleij 
Signed-off-by: Ulf Hansson

mmc: core: Annotate cmd_hdr as __le32

2016-10-10T12:14:49+00:00

Commit f68381a70bb2 (mmc: block: fix packed command header endianness)
correctly fixed endianness handling of packed_cmd_hdr in
mmc_blk_packed_hdr_wrq_prep.

But now, sparse complains about incorrect types:
drivers/mmc/card/block.c:1613:27: sparse: incorrect type in assignment (different base types)
drivers/mmc/card/block.c:1613:27:    expected unsigned int [unsigned] [usertype] 
drivers/mmc/card/block.c:1613:27:    got restricted __le32 [usertype] 
...

So annotate cmd_hdr properly using __le32 to make everyone happy.

Signed-off-by: Jiri Slaby 
Fixes: f68381a70bb2 (mmc: block: fix packed command header endianness)
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson

mmc: card: do away with indirection pointer

2016-09-26T19:31:31+00:00

We have enough vtables in the kernel as it is, we don't need
this one to create even more artificial separation of concerns.

As is proved by the Makefile:

obj-$(CONFIG_MMC_BLOCK)         += mmc_block.o
mmc_block-objs                  := block.o queue.o

block.c and queue.c are baked into the same mmc_block.o object.
So why would one of these objects access a function in the
other object by dereferencing a pointer?

Create a new block.h header file for the single shared function
from block to queue and remove the function pointer and just
call the queue request function.

Apart from making the code more readable, this also makes link
optimizations possible and probably speeds up the call as well.

Signed-off-by: Linus Walleij 
Signed-off-by: Ulf Hansson

block: Fix secure erase

2016-08-16T15:16:51+00:00

Commit 288dab8a35a0 ("block: add a separate operation type for secure
erase") split REQ_OP_SECURE_ERASE from REQ_OP_DISCARD without considering
all the places REQ_OP_DISCARD was being used to mean either. Fix those.

Signed-off-by: Adrian Hunter 
Fixes: 288dab8a35a0 ("block: add a separate operation type for secure erase")
Signed-off-by: Jens Axboe

block, drivers: add REQ_OP_FLUSH operation

2016-06-07T19:41:38+00:00

This adds a REQ_OP_FLUSH operation that is sent to request_fn
based drivers by the block layer's flush code, instead of
sending requests with the request->cmd_flags REQ_FLUSH bit set.

Signed-off-by: Mike Christie 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Jens Axboe