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Groups > linux.kernel > #1590300
| From | Boris Brezillon <boris.brezillon@free-electrons.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers |
| Date | 2017-03-01 13:40 +0100 |
| Message-ID | <tgbHX-334-5@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <tfsrw-5qX-27@gated-at.bofh.it> <tg1yW-43J-11@gated-at.bofh.it> <tg9wt-1CS-3@gated-at.bofh.it> <tga9d-1UD-39@gated-at.bofh.it> <tgaCe-2kf-23@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, 1 Mar 2017 12:18:30 +0100
Frode Isaksen <fisaksen@baylibre.com> wrote:
> On 01/03/2017 11:18, Boris Brezillon wrote:
> > On Wed, 1 Mar 2017 11:09:57 +0100
> > Cyrille Pitchen <cyrille.pitchen@atmel.com> wrote:
> >
> >> Le 28/02/2017 à 22:39, Richard Weinberger a écrit :
> >>> Vignesh,
> >>>
> >>> Am 27.02.2017 um 13:08 schrieb Vignesh R:
> >>>> Filesystems like UBIFS may pass vmalloc'd buffers to SPI NOR layer which
> >>>> will end up in SPI layer. SPI core does try to handle such buffers (see
> >>>> spi_map_buf()) by doing vmalloc_to_page() and creating scatterlist. But,
> >>>> its known that this does not work well with VIVT/aliasing cache
> >>>> architectures.
> >>>> This also fails when buffers are addressed using LPAE (buffers in region
> >>>> higher than 32 bit addressable region), if DMA is 32bit only.
> >>>>
> >>>> Introduce bounce buffers support in SPI NOR framework to handle
> >>>> vmalloc'd buffers. Use a pre-allocated per flash bounce buffer equal to
> >>>> the sector size of the flash. Flash drivers can enable this feature by
> >>>> setting SNOR_F_USE_BOUNCE_BUFFER flag.
> >>>> This would also enable SPI NOR drivers to safely use DMA in their
> >>>> read/write callbacks.
> >>>>
> >>>> Signed-off-by: Vignesh R <vigneshr@ti.com>
> >>>> ---
> >>>> drivers/mtd/spi-nor/spi-nor.c | 30 +++++++++++++++++++++++++++---
> >>>> include/linux/mtd/spi-nor.h | 4 ++++
> >>>> 2 files changed, 31 insertions(+), 3 deletions(-)
> >>>>
> >>>> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> >>>> index 747645c74134..c241fefa5aff 100644
> >>>> --- a/drivers/mtd/spi-nor/spi-nor.c
> >>>> +++ b/drivers/mtd/spi-nor/spi-nor.c
> >>>> @@ -17,6 +17,7 @@
> >>>> #include <linux/mutex.h>
> >>>> #include <linux/math64.h>
> >>>> #include <linux/sizes.h>
> >>>> +#include <linux/mm.h>
> >>>>
> >>>> #include <linux/mtd/mtd.h>
> >>>> #include <linux/of_platform.h>
> >>>> @@ -1205,11 +1206,21 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
> >>>>
> >>>> while (len) {
> >>>> loff_t addr = from;
> >>>> + bool use_bb = false;
> >>>> + u_char *dst_buf = buf;
> >>>> + size_t buf_len = len;
> >>>>
> >>>> if (nor->flags & SNOR_F_S3AN_ADDR_DEFAULT)
> >>>> addr = spi_nor_s3an_addr_convert(nor, addr);
> >>>>
> >>>> - ret = nor->read(nor, addr, len, buf);
> >>>> + if (!virt_addr_valid(buf) && nor->bounce_buf) {
> >> Should we use is_vmalloc_addr() instead of virt_addr_valid() ?
> >>
> >> I guess virt_addr_valid() returns true even for kmalloc'ed buffers
> >> however the copy into the bounce buffer should be avoided for kmalloc'ed
> >> memory.
> > The test is !virt_addr_valid(), so we won't use the bounce buffer for
> > kmalloc-ed regions. I don't remember why we use virt_addr_valid()
> > instead of is_vmalloc_addr() in the NAND framework, but there was a
> > good reason (virt_addr_valid() is more restrictive, but I don't
> > remember why it's safer :))
> I think virt_addr_valid() picks up both kmap'ed and vmalloc'ed pages as not valid...
Thanks for the remainder. So we definitely want to use
virt_addr_valid() here.
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[RFC PATCH 0/2] mtd: spi-nor: Handle vmalloc'd buffers Vignesh R <vigneshr@ti.com> - 2017-02-27 13:20 +0100
[RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Vignesh R <vigneshr@ti.com> - 2017-02-27 13:20 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Richard Weinberger <richard@nod.at> - 2017-02-28 22:50 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Vignesh R <vigneshr@ti.com> - 2017-03-01 09:00 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Cyrille Pitchen <cyrille.pitchen@atmel.com> - 2017-03-01 12:10 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Frode Isaksen <fisaksen@baylibre.com> - 2017-03-01 12:50 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-01 13:40 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-01 15:30 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Cyrille Pitchen <cyrille.pitchen@atmel.com> - 2017-03-01 15:40 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Cyrille Pitchen <cyrille.pitchen@atmel.com> - 2017-03-01 15:30 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Mark Brown <broonie@kernel.org> - 2017-03-01 17:00 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-01 17:20 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-01 18:00 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Frode Isaksen <fisaksen@baylibre.com> - 2017-03-02 10:10 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-02 16:00 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Frode Isaksen <fisaksen@baylibre.com> - 2017-03-02 16:20 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-02 17:00 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Frode Isaksen <fisaksen@baylibre.com> - 2017-03-03 10:10 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Cyrille Pitchen <cyrille.pitchen@atmel.com> - 2017-03-02 17:50 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Mark Brown <broonie@kernel.org> - 2017-03-02 19:20 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-03 04:20 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Mark Brown <broonie@kernel.org> - 2017-03-03 14:20 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Vignesh R <vigneshr@ti.com> - 2017-03-06 12:50 +0100
Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support Vignesh R <vigneshr@ti.com> - 2017-03-03 23:10 +0100
[RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Vignesh R <vigneshr@ti.com> - 2017-02-27 13:20 +0100
Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Richard Weinberger <richard@nod.at> - 2017-03-01 02:50 +0100
Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Vignesh R <vigneshr@ti.com> - 2017-03-01 09:00 +0100
Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Cyrille Pitchen <cyrille.pitchen@atmel.com> - 2017-03-01 11:20 +0100
Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-01 12:00 +0100
Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Frode Isaksen <fisaksen@baylibre.com> - 2017-03-01 12:30 +0100
Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-01 13:40 +0100
Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Vignesh R <vigneshr@ti.com> - 2017-03-01 13:00 +0100
Re: [RFC PATCH 0/2] mtd: spi-nor: Handle vmalloc'd buffers Frode Isaksen <fisaksen@baylibre.com> - 2017-02-27 17:00 +0100
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