From d9018976cdb6eefc62a7ba79a405f6c9661b08a7 Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Fri, 28 Jul 2017 13:50:42 +0300 Subject: [PATCH] mfd: lpc_ich: Do not touch SPI-NOR write protection bit on Haswell/Broadwell Mime-version: 1.0 Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 8bit Git-commit: d9018976cdb6eefc62a7ba79a405f6c9661b08a7 Patch-mainline: v4.14-rc1 References: bsc#1051510 At least on Lenovo Thinkpad Yoga, the BIOS seems to monitor the SPI-NOR write protection bit and if it is flipped to read/write it assumes the BIOS configuration was changed on next reboot. It then, for unknown reasons, resets the BIOS settings back to default. We can prevent this by just leaving the write protection bit intact and let the SPI-NOR driver know whether the device is writable or not. In case of this particular Lenovo the SPI-NOR flash will be exposed as read-only. Fixes: ff00d7a32a1b ("mfd: lpc_ich: Add support for SPI serial flash host controller") Link: https://bugzilla.kernel.org/show_bug.cgi?id=195951 Reported-by: Abdó Roig-Marange Signed-off-by: Mika Westerberg Signed-off-by: Lee Jones Acked-by: Takashi Iwai --- drivers/mfd/lpc_ich.c | 10 ---------- 1 file changed, 10 deletions(-) --- a/drivers/mfd/lpc_ich.c +++ b/drivers/mfd/lpc_ich.c @@ -1119,17 +1119,7 @@ static int lpc_ich_init_spi(struct pci_d res->start = spi_base + SPIBASE_LPT; res->end = res->start + SPIBASE_LPT_SZ - 1; - /* - * Try to make the flash chip writeable now by - * setting BCR_WPD. It it fails we tell the driver - * that it can only read the chip. - */ pci_read_config_dword(dev, BCR, &bcr); - if (!(bcr & BCR_WPD)) { - bcr |= BCR_WPD; - pci_write_config_dword(dev, BCR, bcr); - pci_read_config_dword(dev, BCR, &bcr); - } info->writeable = !!(bcr & BCR_WPD); } break;