Patchwork [REPOST] mtd: extend plat_nand for (read|write)_buf

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Submitter Alexander Clouter
Date May 11, 2009, 6:28 p.m.
Message ID <20090511182801.GK32684@woodchuck>
Download mbox | patch
Permalink /patch/27058/
State New
Headers show

Comments

Alexander Clouter - May 11, 2009, 6:28 p.m.
This patch adds (write|read)_buf callbacks to plat_nand.

The NAND on the TS-7800 provisioned by the FPGA allows readw() and 
readl() to be used which gives a 2.5x speed up.  To be able to use this 
from the plat_nand driver a hook for read_buf (and also write_buf whilst 
we are in there) need to be made available.  This patch adds the hook.

This is a repost[1] of a feature asked for before[2], plus other helpful 
patches to plat_nand[3] would be welcomed if at all possible too.

[1] http://lists.infradead.org/pipermail/linux-mtd/2009-March/024747.html
[2] http://lists.infradead.org/pipermail/linux-mtd/2007-October/019659.html
[3] http://lists.infradead.org/pipermail/linux-mtd/2009-March/024780.html

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
---
Artem Bityutskiy - May 15, 2009, 1:51 p.m.
On Mon, 2009-05-11 at 19:28 +0100, Alexander Clouter wrote:
> This patch adds (write|read)_buf callbacks to plat_nand.
> 
> The NAND on the TS-7800 provisioned by the FPGA allows readw() and 
> readl() to be used which gives a 2.5x speed up.  To be able to use this 
> from the plat_nand driver a hook for read_buf (and also write_buf whilst 
> we are in there) need to be made available.  This patch adds the hook.
> 
> This is a repost[1] of a feature asked for before[2], plus other helpful 
> patches to plat_nand[3] would be welcomed if at all possible too.
> 
> [1] http://lists.infradead.org/pipermail/linux-mtd/2009-March/024747.html
> [2] http://lists.infradead.org/pipermail/linux-mtd/2007-October/019659.html
> [3] http://lists.infradead.org/pipermail/linux-mtd/2009-March/024780.html
> 
> Signed-off-by: Alexander Clouter <alex@digriz.org.uk>

I think this should be submitted with the user at the same
time. Adding hooks without having a user is not very good.
E.g., you may find out later that this does not help, or
cancel your project, or end up with different call-backs,
etc.

You may keep this patch privately, work on your NAND driver,
and when you have it ready, you submit it with this at the
same time.
Alexander Clouter - May 15, 2009, 3:05 p.m.
Hi,

* Artem Bityutskiy <dedekind@infradead.org> [2009-05-15 16:51:00+0300]:
> 
> On Mon, 2009-05-11 at 19:28 +0100, Alexander Clouter wrote:
> > This patch adds (write|read)_buf callbacks to plat_nand.
> > 
> > The NAND on the TS-7800 provisioned by the FPGA allows readw() and 
> > readl() to be used which gives a 2.5x speed up.  To be able to use this 
> > from the plat_nand driver a hook for read_buf (and also write_buf whilst 
> > we are in there) need to be made available.  This patch adds the hook.
> > 
> > This is a repost[1] of a feature asked for before[2], plus other helpful 
> > patches to plat_nand[3] would be welcomed if at all possible too.
> > 
> > [1] http://lists.infradead.org/pipermail/linux-mtd/2009-March/024747.html
> > [2] http://lists.infradead.org/pipermail/linux-mtd/2007-October/019659.html
> > [3] http://lists.infradead.org/pipermail/linux-mtd/2009-March/024780.html
> > 
> > Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
> 
> I think this should be submitted with the user at the same
> time. Adding hooks without having a user is not very good.
> E.g., you may find out later that this does not help, or
> cancel your project, or end up with different call-backs,
> etc.
> 
In the case of read/write_buf...there is no other way, I'm all ears if 
you know how I can do (read|write)(w|l) with plat_nand *now*?

I just pulled off this type of manoeuvre for a HW RNG driver:

http://lkml.indiana.edu/hypermail/linux/kernel/0902.2/02727.html
http://git.marvell.com/?p=orion.git;a=commit;h=8be7b57dea0467324ad4545334c5e35c18f0814b

I doubt the ARM people would be happy if I push ARM patches through the 
MTD sub-system :)

> You may keep this patch privately, work on your NAND driver,
> and when you have it ready, you submit it with this at the
> same time.
> 
Erm, it's been ready for a *long* time, about a year[1], and is being 
used.  Recently the bits of my plat_nand impementation[2] is on it's way 
to going mainline (Orion -> ARM -> Linus):

http://git.marvell.com/?p=orion.git;a=commit;h=75bb6b9aab3255f440ef4e72a31978d1681105d6

Cheers

[1] http://tech.groups.yahoo.com/group/ts-7000/message/11616
[2] http://lists.infradead.org/pipermail/linux-mtd/2009-February/024555.html
Artem Bityutskiy - May 15, 2009, 3:31 p.m.
On Fri, 2009-05-15 at 16:05 +0100, Alexander Clouter wrote:
> > You may keep this patch privately, work on your NAND driver,
> > and when you have it ready, you submit it with this at the
> > same time.
> > 
> Erm, it's been ready for a *long* time, about a year[1], and is being 
> used.  Recently the bits of my plat_nand impementation[2] is on it's way 
> to going mainline (Orion -> ARM -> Linus):

Ok, I thought you do not use this so far.

I've pushed your patch to l2-mtd-2.6.git. This does not guarantee
anything, just means I'll ping David to look at it and send upstream.

Patch

diff --git a/drivers/mtd/nand/plat_nand.c b/drivers/mtd/nand/plat_nand.c
index 86e1d08..4cdec46 100644
--- a/drivers/mtd/nand/plat_nand.c
+++ b/drivers/mtd/nand/plat_nand.c
@@ -61,6 +61,8 @@  static int __devinit plat_nand_probe(struct platform_device *pdev)
 	data->chip.cmd_ctrl = pdata->ctrl.cmd_ctrl;
 	data->chip.dev_ready = pdata->ctrl.dev_ready;
 	data->chip.select_chip = pdata->ctrl.select_chip;
+	data->chip.write_buf = pdata->ctrl.write_buf;
+	data->chip.read_buf = pdata->ctrl.read_buf;
 	data->chip.chip_delay = pdata->chip.chip_delay;
 	data->chip.options |= pdata->chip.options;
 
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 7efb9be..0e35375 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -584,6 +584,8 @@  struct platform_nand_chip {
  * @select_chip:	platform specific chip select function
  * @cmd_ctrl:		platform specific function for controlling
  *			ALE/CLE/nCE. Also used to write command and address
+ * @write_buf:		platform specific function for write buffer
+ * @read_buf:		platform specific function for read buffer
  * @priv:		private data to transport driver specific settings
  *
  * All fields are optional and depend on the hardware driver requirements
@@ -594,6 +596,10 @@  struct platform_nand_ctrl {
 	void		(*select_chip)(struct mtd_info *mtd, int chip);
 	void		(*cmd_ctrl)(struct mtd_info *mtd, int dat,
 				    unsigned int ctrl);
+	void		(*write_buf)(struct mtd_info *mtd,
+				    const uint8_t *buf, int len);
+	void		(*read_buf)(struct mtd_info *mtd,
+				    uint8_t *buf, int len);
 	void		*priv;
 };