From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.free-electrons.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1cj1LA-0008VP-Rk for linux-mtd@lists.infradead.org; Wed, 01 Mar 2017 10:18:38 +0000 Date: Wed, 1 Mar 2017 11:18:05 +0100 From: Boris Brezillon To: Cyrille Pitchen Cc: Richard Weinberger , Vignesh R , David Woodhouse , Brian Norris , Marek Vasut , , , , Frode Isaksen , Subject: Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Message-ID: <20170301111805.0eb23b76@bbrezillon> In-Reply-To: <65b4a156-f2a8-4c5e-4399-2024a147d5ec@atmel.com> References: <20170227120839.16545-1-vigneshr@ti.com> <20170227120839.16545-2-vigneshr@ti.com> <8e441369-5c15-d711-1789-b55eadf33c8f@nod.at> <65b4a156-f2a8-4c5e-4399-2024a147d5ec@atmel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 1 Mar 2017 11:09:57 +0100 Cyrille Pitchen wrote: > Le 28/02/2017 =C3=A0 22:39, Richard Weinberger a =C3=A9crit : > > Vignesh, > >=20 > > Am 27.02.2017 um 13:08 schrieb Vignesh R: =20 > >> Filesystems like UBIFS may pass vmalloc'd buffers to SPI NOR layer whi= ch > >> 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. Bu= t, > >> its known that this does not work well with VIVT/aliasing cache > >> architectures. > >> This also fails when buffers are addressed using LPAE (buffers in regi= on > >> 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 > >> --- > >> 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-n= or.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 > >> #include > >> #include > >> +#include > >> =20 > >> #include > >> #include > >> @@ -1205,11 +1206,21 @@ static int spi_nor_read(struct mtd_info *mtd, = loff_t from, size_t len, > >> =20 > >> while (len) { > >> loff_t addr =3D from; > >> + bool use_bb =3D false; > >> + u_char *dst_buf =3D buf; > >> + size_t buf_len =3D len; > >> =20 > >> if (nor->flags & SNOR_F_S3AN_ADDR_DEFAULT) > >> addr =3D spi_nor_s3an_addr_convert(nor, addr); > >> =20 > >> - ret =3D nor->read(nor, addr, len, buf); > >> + if (!virt_addr_valid(buf) && nor->bounce_buf) { =20 >=20 > Should we use is_vmalloc_addr() instead of virt_addr_valid() ? >=20 > 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 :)) From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [RFC PATCH 1/2] mtd: spi-nor: Introduce bounce buffer to handle vmalloc'd buffers Date: Wed, 1 Mar 2017 11:18:05 +0100 Message-ID: <20170301111805.0eb23b76@bbrezillon> References: <20170227120839.16545-1-vigneshr@ti.com> <20170227120839.16545-2-vigneshr@ti.com> <8e441369-5c15-d711-1789-b55eadf33c8f@nod.at> <65b4a156-f2a8-4c5e-4399-2024a147d5ec@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <65b4a156-f2a8-4c5e-4399-2024a147d5ec@atmel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-mtd" Errors-To: linux-mtd-bounces+gldm-linux-mtd-36=gmane.org@lists.infradead.org To: Cyrille Pitchen Cc: Frode Isaksen , linux-omap@vger.kernel.org, Vignesh R , Richard Weinberger , linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org, Marek Vasut , linux-mtd@lists.infradead.org, Brian Norris , David Woodhouse List-Id: linux-omap@vger.kernel.org T24gV2VkLCAxIE1hciAyMDE3IDExOjA5OjU3ICswMTAwCkN5cmlsbGUgUGl0Y2hlbiA8Y3lyaWxs ZS5waXRjaGVuQGF0bWVsLmNvbT4gd3JvdGU6Cgo+IExlIDI4LzAyLzIwMTcgw6AgMjI6MzksIFJp Y2hhcmQgV2VpbmJlcmdlciBhIMOpY3JpdCA6Cj4gPiBWaWduZXNoLAo+ID4gCj4gPiBBbSAyNy4w Mi4yMDE3IHVtIDEzOjA4IHNjaHJpZWIgVmlnbmVzaCBSOiAgCj4gPj4gRmlsZXN5c3RlbXMgbGlr ZSBVQklGUyBtYXkgcGFzcyB2bWFsbG9jJ2QgYnVmZmVycyB0byBTUEkgTk9SIGxheWVyIHdoaWNo Cj4gPj4gd2lsbCBlbmQgdXAgaW4gU1BJIGxheWVyLiBTUEkgY29yZSBkb2VzIHRyeSB0byBoYW5k bGUgc3VjaCBidWZmZXJzIChzZWUKPiA+PiBzcGlfbWFwX2J1ZigpKSBieSBkb2luZyB2bWFsbG9j X3RvX3BhZ2UoKSBhbmQgY3JlYXRpbmcgc2NhdHRlcmxpc3QuIEJ1dCwKPiA+PiBpdHMga25vd24g dGhhdCB0aGlzIGRvZXMgbm90IHdvcmsgd2VsbCB3aXRoIFZJVlQvYWxpYXNpbmcgY2FjaGUKPiA+ PiBhcmNoaXRlY3R1cmVzLgo+ID4+IFRoaXMgYWxzbyBmYWlscyB3aGVuIGJ1ZmZlcnMgYXJlIGFk ZHJlc3NlZCB1c2luZyBMUEFFIChidWZmZXJzIGluIHJlZ2lvbgo+ID4+IGhpZ2hlciB0aGFuIDMy IGJpdCBhZGRyZXNzYWJsZSByZWdpb24pLCBpZiBETUEgaXMgMzJiaXQgb25seS4KPiA+Pgo+ID4+ IEludHJvZHVjZSBib3VuY2UgYnVmZmVycyBzdXBwb3J0IGluIFNQSSBOT1IgZnJhbWV3b3JrIHRv IGhhbmRsZQo+ID4+IHZtYWxsb2MnZCBidWZmZXJzLiBVc2UgYSBwcmUtYWxsb2NhdGVkIHBlciBm bGFzaCBib3VuY2UgYnVmZmVyIGVxdWFsIHRvCj4gPj4gdGhlIHNlY3RvciBzaXplIG9mIHRoZSBm bGFzaC4gRmxhc2ggZHJpdmVycyBjYW4gZW5hYmxlIHRoaXMgZmVhdHVyZSBieQo+ID4+IHNldHRp bmcgU05PUl9GX1VTRV9CT1VOQ0VfQlVGRkVSIGZsYWcuCj4gPj4gVGhpcyB3b3VsZCBhbHNvIGVu YWJsZSBTUEkgTk9SIGRyaXZlcnMgdG8gc2FmZWx5IHVzZSBETUEgaW4gdGhlaXIKPiA+PiByZWFk L3dyaXRlIGNhbGxiYWNrcy4KPiA+Pgo+ID4+IFNpZ25lZC1vZmYtYnk6IFZpZ25lc2ggUiA8dmln bmVzaHJAdGkuY29tPgo+ID4+IC0tLQo+ID4+ICBkcml2ZXJzL210ZC9zcGktbm9yL3NwaS1ub3Iu YyB8IDMwICsrKysrKysrKysrKysrKysrKysrKysrKysrKy0tLQo+ID4+ICBpbmNsdWRlL2xpbnV4 L210ZC9zcGktbm9yLmggICB8ICA0ICsrKysKPiA+PiAgMiBmaWxlcyBjaGFuZ2VkLCAzMSBpbnNl cnRpb25zKCspLCAzIGRlbGV0aW9ucygtKQo+ID4+Cj4gPj4gZGlmZiAtLWdpdCBhL2RyaXZlcnMv bXRkL3NwaS1ub3Ivc3BpLW5vci5jIGIvZHJpdmVycy9tdGQvc3BpLW5vci9zcGktbm9yLmMKPiA+ PiBpbmRleCA3NDc2NDVjNzQxMzQuLmMyNDFmZWZhNWFmZiAxMDA2NDQKPiA+PiAtLS0gYS9kcml2 ZXJzL210ZC9zcGktbm9yL3NwaS1ub3IuYwo+ID4+ICsrKyBiL2RyaXZlcnMvbXRkL3NwaS1ub3Iv c3BpLW5vci5jCj4gPj4gQEAgLTE3LDYgKzE3LDcgQEAKPiA+PiAgI2luY2x1ZGUgPGxpbnV4L211 dGV4Lmg+Cj4gPj4gICNpbmNsdWRlIDxsaW51eC9tYXRoNjQuaD4KPiA+PiAgI2luY2x1ZGUgPGxp bnV4L3NpemVzLmg+Cj4gPj4gKyNpbmNsdWRlIDxsaW51eC9tbS5oPgo+ID4+ICAKPiA+PiAgI2lu Y2x1ZGUgPGxpbnV4L210ZC9tdGQuaD4KPiA+PiAgI2luY2x1ZGUgPGxpbnV4L29mX3BsYXRmb3Jt Lmg+Cj4gPj4gQEAgLTEyMDUsMTEgKzEyMDYsMjEgQEAgc3RhdGljIGludCBzcGlfbm9yX3JlYWQo c3RydWN0IG10ZF9pbmZvICptdGQsIGxvZmZfdCBmcm9tLCBzaXplX3QgbGVuLAo+ID4+ICAKPiA+ PiAgCXdoaWxlIChsZW4pIHsKPiA+PiAgCQlsb2ZmX3QgYWRkciA9IGZyb207Cj4gPj4gKwkJYm9v bCB1c2VfYmIgPSBmYWxzZTsKPiA+PiArCQl1X2NoYXIgKmRzdF9idWYgPSBidWY7Cj4gPj4gKwkJ c2l6ZV90IGJ1Zl9sZW4gPSBsZW47Cj4gPj4gIAo+ID4+ICAJCWlmIChub3ItPmZsYWdzICYgU05P Ul9GX1MzQU5fQUREUl9ERUZBVUxUKQo+ID4+ICAJCQlhZGRyID0gc3BpX25vcl9zM2FuX2FkZHJf Y29udmVydChub3IsIGFkZHIpOwo+ID4+ICAKPiA+PiAtCQlyZXQgPSBub3ItPnJlYWQobm9yLCBh ZGRyLCBsZW4sIGJ1Zik7Cj4gPj4gKwkJaWYgKCF2aXJ0X2FkZHJfdmFsaWQoYnVmKSAmJiBub3It PmJvdW5jZV9idWYpIHsgIAo+IAo+IFNob3VsZCB3ZSB1c2UgaXNfdm1hbGxvY19hZGRyKCkgaW5z dGVhZCBvZiB2aXJ0X2FkZHJfdmFsaWQoKSA/Cj4gCj4gSSBndWVzcyB2aXJ0X2FkZHJfdmFsaWQo KSByZXR1cm5zIHRydWUgZXZlbiBmb3Iga21hbGxvYydlZCBidWZmZXJzCj4gaG93ZXZlciB0aGUg Y29weSBpbnRvIHRoZSBib3VuY2UgYnVmZmVyIHNob3VsZCBiZSBhdm9pZGVkIGZvciBrbWFsbG9j J2VkCj4gbWVtb3J5LgoKVGhlIHRlc3QgaXMgIXZpcnRfYWRkcl92YWxpZCgpLCBzbyB3ZSB3b24n dCB1c2UgdGhlIGJvdW5jZSBidWZmZXIgZm9yCmttYWxsb2MtZWQgcmVnaW9ucy4gSSBkb24ndCBy ZW1lbWJlciB3aHkgd2UgdXNlIHZpcnRfYWRkcl92YWxpZCgpCmluc3RlYWQgb2YgaXNfdm1hbGxv Y19hZGRyKCkgaW4gdGhlIE5BTkQgZnJhbWV3b3JrLCBidXQgdGhlcmUgd2FzIGEKZ29vZCByZWFz b24gKHZpcnRfYWRkcl92YWxpZCgpIGlzIG1vcmUgcmVzdHJpY3RpdmUsIGJ1dCBJIGRvbid0CnJl bWVtYmVyIHdoeSBpdCdzIHNhZmVyIDopKQoKCgoKX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fCkxpbnV4IE1URCBkaXNjdXNzaW9uIG1haWxpbmcg bGlzdApodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LW10 ZC8K