From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from arrakis.dune.hu ([78.24.191.176]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a2njv-0004qj-Dk for linux-mtd@lists.infradead.org; Sat, 28 Nov 2015 22:13:08 +0000 Subject: Re: [PATCH] Revert "mtd: spi-nor: disable protection for Winbond flash at startup" To: Ezequiel Garcia References: <1448555221-24257-1-git-send-email-nbd@openwrt.org> Cc: "linux-mtd@lists.infradead.org" , Brian Norris From: Felix Fietkau Message-ID: <565A26D6.5090504@openwrt.org> Date: Sat, 28 Nov 2015 23:12:38 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 2015-11-28 22:56, Ezequiel Garcia wrote: > On 26 November 2015 at 13:27, Felix Fietkau wrote: >> This reverts commit c6fc2171b249e73745c497b578b417a2946f1b2f. >> >> This commit is breaking read access on at least s25fl064k, but also >> possibly other Spansion flash chips. >> >> Any mtd read seems to succeed, but simply returns a zero-filled buffer. >> >> Signed-off-by: Felix Fietkau >> --- >> drivers/mtd/spi-nor/spi-nor.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c >> index 4988390..8b8842e 100644 >> --- a/drivers/mtd/spi-nor/spi-nor.c >> +++ b/drivers/mtd/spi-nor/spi-nor.c >> @@ -1194,14 +1194,13 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode) >> mutex_init(&nor->lock); >> >> /* >> - * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up >> - * with the software protection bits set >> + * Atmel, SST and Intel/Numonyx serial nor tend to power >> + * up with the software protection bits set >> */ >> >> if (JEDEC_MFR(info) == SNOR_MFR_ATMEL || >> JEDEC_MFR(info) == SNOR_MFR_INTEL || >> - JEDEC_MFR(info) == SNOR_MFR_SST || >> - JEDEC_MFR(info) == SNOR_MFR_WINBOND) { >> + JEDEC_MFR(info) == SNOR_MFR_SST) { >> write_enable(nor); >> write_sr(nor, 0); >> } > > As Brian mentioned, this looks definitely fishy. > > IIUC, the above statement is trying to unlock flashes that power-up as > locked. But you say your flash is still locked after booting? And > moreover, removing the unlock quirk fixes it? The flash isn't locked when the system boots, reads and writes work just fine. > I think a more complete description of your problem might help us fix > this the right way. Perhaps the above line clearing the status > register is wrong? Without the write_enable/write_sr, the flash is readable and writable. With it, any reads return only null-bytes as data. What other info about the problem do you need? I think it probably works just fine for Winbond flashes, but unfortunately this also affects some Spansion flash chips with IDs that start with 0xef (SNOR_MFR_WINBOND). - Felix