From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f42.google.com (mail-yw0-f42.google.com [209.85.213.42]) by ozlabs.org (Postfix) with ESMTP id 1EFBAB70B5 for ; Mon, 26 Jul 2010 17:55:29 +1000 (EST) Received: by ywi6 with SMTP id 6so492160ywi.15 for ; Mon, 26 Jul 2010 00:55:28 -0700 (PDT) MIME-Version: 1.0 Sender: glikely@secretlab.ca In-Reply-To: <73839B4A0818E747864426270AC332C305400642@zmy16exm20.fsl.freescale.net> References: <1279591705-7574-1-git-send-email-Mingkai.hu@freescale.com> <1279591705-7574-2-git-send-email-Mingkai.hu@freescale.com> <1279591705-7574-3-git-send-email-Mingkai.hu@freescale.com> <1279591705-7574-4-git-send-email-Mingkai.hu@freescale.com> <1279591705-7574-5-git-send-email-Mingkai.hu@freescale.com> <20100726003028.GC25419@angua.secretlab.ca> <73839B4A0818E747864426270AC332C305400642@zmy16exm20.fsl.freescale.net> From: Grant Likely Date: Mon, 26 Jul 2010 01:55:08 -0600 Message-ID: Subject: Re: [PATCH 4/6] mtd: m25p80: change the read function to read page by page To: Hu Mingkai-B21284 Content-Type: text/plain; charset=ISO-8859-1 Cc: linuxppc-dev@ozlabs.org, Zang Roy-R61911 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Jul 26, 2010 at 1:33 AM, Hu Mingkai-B21284 w= rote: > > >> -----Original Message----- >> From: Grant Likely [mailto:glikely@secretlab.ca] On Behalf Of >> Grant Likely >> Sent: Monday, July 26, 2010 8:30 AM >> To: Hu Mingkai-B21284 >> Cc: linuxppc-dev@ozlabs.org; galak@kernel.crashing.org; Zang >> Roy-R61911 >> Subject: Re: [PATCH 4/6] mtd: m25p80: change the read >> function to read page by page >> >> On Tue, Jul 20, 2010 at 10:08:23AM +0800, Mingkai Hu wrote: >> > For Freescale's eSPI controller, the max transaction length >> one time >> > is limitted by the SPCOM[TRANSLEN] field which is 0x10000. When used >> > mkfs.ext2 command to create ext2 filesystem on the flash, the read >> > length will exceed the max value of the SPCOM[TRANSLEN] field, so >> > change the read function to read page by page. >> > >> > For other SPI flash driver, also needed to change the read >> function if >> > used the eSPI controller. >> > >> > Signed-off-by: Mingkai Hu >> > --- >> > =A0drivers/mtd/devices/m25p80.c | =A0 18 ++++++++++++++---- >> > =A01 files changed, 14 insertions(+), 4 deletions(-) >> > >> > diff --git a/drivers/mtd/devices/m25p80.c >> > b/drivers/mtd/devices/m25p80.c index 81e49a9..6cbe6b1 100644 >> > --- a/drivers/mtd/devices/m25p80.c >> > +++ b/drivers/mtd/devices/m25p80.c >> > @@ -317,6 +317,7 @@ static int m25p80_read(struct mtd_info >> *mtd, loff_t from, size_t len, >> > =A0 =A0 struct m25p *flash =3D mtd_to_m25p(mtd); >> > =A0 =A0 struct spi_transfer t[2]; >> > =A0 =A0 struct spi_message m; >> > + =A0 u32 i, page_size =3D 0; >> > >> > =A0 =A0 DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %zd\n", >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 dev_name(&flash->spi->dev), __= func__, >> "from", @@ -341,7 +342,6 @@ >> > static int m25p80_read(struct mtd_info *mtd, loff_t from, >> size_t len, >> > =A0 =A0 spi_message_add_tail(&t[0], &m); >> > >> > =A0 =A0 t[1].rx_buf =3D buf; >> > - =A0 t[1].len =3D len; >> > =A0 =A0 spi_message_add_tail(&t[1], &m); >> > >> > =A0 =A0 /* Byte count starts at zero. */ >> > @@ -364,11 +364,21 @@ static int m25p80_read(struct mtd_info *mtd, >> > loff_t from, size_t len, >> > >> > =A0 =A0 /* Set up the write data buffer. */ >> > =A0 =A0 flash->command[0] =3D OPCODE_READ; >> > - =A0 m25p_addr2cmd(flash, from, flash->command); >> > >> > - =A0 spi_sync(flash->spi, &m); >> > + =A0 for (i =3D page_size; i < len; i +=3D page_size) { >> > + =A0 =A0 =A0 =A0 =A0 page_size =3D len - i; >> > + =A0 =A0 =A0 =A0 =A0 if (page_size > flash->page_size) >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 page_size =3D flash->page_size; >> > >> > - =A0 *retlen =3D m.actual_length - m25p_cmdsz(flash) - >> FAST_READ_DUMMY_BYTE; >> > + =A0 =A0 =A0 =A0 =A0 m25p_addr2cmd(flash, from + i, flash->command); >> > + =A0 =A0 =A0 =A0 =A0 t[1].len =3D page_size; >> > + =A0 =A0 =A0 =A0 =A0 t[1].rx_buf =3D buf + i; >> > + >> > + =A0 =A0 =A0 =A0 =A0 spi_sync(flash->spi, &m); >> > + >> > + =A0 =A0 =A0 =A0 =A0 *retlen +=3D m.actual_length - m25p_cmdsz(flash) >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 - FAST_READ_DUMMY_BYTE; >> > + =A0 } >> >> This patch seems to cripple all users just because eSPI >> cannot handle it. =A0Am I reading it wrong? >> > > You're right, this will cripple all users. > > At first, I want to contain this specific code with CONFIG_SPI_FSL_ESPI > option, > or register a specific read function like: > > #ifdef CONFIG_SPI_FSL_ESPI > =A0 =A0 =A0 =A0flash->mtd.read =3D m25p80_read_espi; > #endif > > but this will make the code looks arguly, And it is multiplatform-unfriendly. > are there other ways? You need to select the correct transfer behaviour at driver probe time. You'll need a way to indicate that the spi_master isn't able to handle your transfer request. I'd need to think about it more to come up with a concrete suggestion. g.