From: Vignesh Raghavendra <vigneshr@ti.com> To: <Tudor.Ambarus@microchip.com>, <miquel.raynal@bootlin.com>, <richard@nod.at> Cc: marek.vasut@gmail.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, tmaimon77@gmail.com, bbrezillon@kernel.org Subject: Re: [PATCH v4 1/3] mtd: spi-nor: always use bounce buffer for register read/writes Date: Mon, 5 Aug 2019 16:08:57 +0530 Message-ID: <2b10c18a-e955-31b8-b3e0-c3df83508756@ti.com> (raw) In-Reply-To: <b125bf29-f1fd-6d33-4a7c-49cb94ef1488@microchip.com> On 05/08/19 2:36 PM, Tudor.Ambarus@microchip.com wrote: > > > On 08/01/2019 07:22 PM, Vignesh Raghavendra wrote: >> External E-Mail >> >> >> spi-mem layer expects all buffers passed to it to be DMA'able. But >> spi-nor layer mostly allocates buffers on stack for reading/writing to >> registers and therefore are not DMA'able. Introduce bounce buffer to be >> used to read/write to registers. This ensures that buffer passed to >> spi-mem layer during register read/writes is DMA'able. With this change >> nor->cmd-buf is no longer used, so drop it. >> >> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> >> Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com> >> --- >> >> v4: >> Avoid memcpy during READID >> >> v3: new patch >> >> drivers/mtd/spi-nor/spi-nor.c | 70 ++++++++++++++++++++--------------- >> include/linux/mtd/spi-nor.h | 7 +++- >> 2 files changed, 45 insertions(+), 32 deletions(-) >> >> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c >> index 03cc788511d5..e02376e1127b 100644 >> --- a/drivers/mtd/spi-nor/spi-nor.c >> +++ b/drivers/mtd/spi-nor/spi-nor.c > > cut > >> /** >> @@ -1404,9 +1401,11 @@ static int write_sr_cr(struct spi_nor *nor, u8 *sr_cr) >> { >> int ret; >> >> + memcpy(nor->bouncebuf, sr_cr, 2); > > I'm thinking out loud. This can be avoided by forcing all the callers to use > nor->bouncebuf. That would result in a: > I can make this change and make all callers use nor->bouncebuf in next version. > static int write_sr(struct spi_nor *nor, size_t len) > > write_sr_cr() can be removed. Memcopying 2 bytes is a small price to pay, we can > keep things as they are, to not be too invasive. But if you think that this idea > is worth it, tell. > Sounds good to me. But replacing write_sr_cr() with above defintion of write_sr() should be a patch IMO> >> + >> write_enable(nor); >> >> - ret = nor->write_reg(nor, SPINOR_OP_WRSR, sr_cr, 2); >> + ret = nor->write_reg(nor, SPINOR_OP_WRSR, nor->bouncebuf, 2); >> if (ret < 0) { >> dev_err(nor->dev, >> "error while writing configuration register\n"); > > cut > >> @@ -2177,9 +2176,10 @@ static const struct flash_info spi_nor_ids[] = { >> static const struct flash_info *spi_nor_read_id(struct spi_nor *nor) >> { >> int tmp; >> - u8 id[SPI_NOR_MAX_ID_LEN]; >> + u8 *id; >> const struct flash_info *info; >> >> + id = nor->bouncebuf; > > nit: do init at declaration. > Ok. > Also, you missed a place in which you can use the bouncebuf, search by "read_reg(": > ret = nor->read_reg(nor, SPINOR_OP_XRDSR, &val, 1); > Indeed, will fix in next version! > Cheers, > ta > -- Regards Vignesh ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply index Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-01 16:22 [PATCH v4 0/3] Merge m25p80 into spi-nor Vignesh Raghavendra 2019-08-01 16:22 ` [PATCH v4 1/3] mtd: spi-nor: always use bounce buffer for register read/writes Vignesh Raghavendra 2019-08-05 9:06 ` Tudor.Ambarus 2019-08-05 10:38 ` Vignesh Raghavendra [this message] 2019-08-05 11:24 ` Tudor.Ambarus 2019-08-01 16:22 ` [PATCH v4 2/3] mtd: spi-nor: Move m25p80 code in spi-nor.c Vignesh Raghavendra 2019-08-05 10:25 ` Tudor.Ambarus 2019-08-05 11:10 ` Vignesh Raghavendra 2019-08-05 11:51 ` Tudor.Ambarus 2019-08-05 12:31 ` Vignesh Raghavendra 2019-08-01 16:22 ` [PATCH v4 3/3] mtd: spi-nor: Rework hwcaps selection for the spi-mem case Vignesh Raghavendra 2019-08-05 17:45 ` Tudor.Ambarus
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