From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Nelson Date: Mon, 7 Dec 2015 07:08:52 -0700 Subject: [U-Boot] [PATCH] imx_common: check for Serial Downloader in spl_boot_device In-Reply-To: <5665579F.1080808@denx.de> References: <1449219732-5396-1-git-send-email-sbabic@denx.de> <56634586.6050200@nelint.com> <5665579F.1080808@denx.de> Message-ID: <566592F4.4090901@nelint.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Stefano, On 12/07/2015 02:55 AM, Stefano Babic wrote: > Hi Eric, > > On 05/12/2015 21:13, Eric Nelson wrote: >> Hi Stefano, >> >> On 12/04/2015 02:02 AM, Stefano Babic wrote: >>> Check for bmode before reading the boot device >>> to check if a serial downloader is started, >>> and returns UART if the serial downloader is set, >>> letting SPL to wait for an image if >>> CONFIG_SPL_YMODEM_SUPPORT is set. >>> ... >> Separately, what's your thought about enabling this when the >> system is reset through "bmode usb"? >> >> http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/cpu/armv7/mx6/soc.c;h=bf5ae8cdffd8b0887291249332b06f66dc644832;hb=HEAD#l389 >> >> Since the gpr9 value in this mode is 0x00000001, the switch >> statement currently falls into the NOR/OneNAND block, which >> is pretty useless. > > I agree with you, in fact it does not work - but I do not see a way to > inform the ROM that next time it should run with USB as boot device. > From the fusemap, I tried to set BOOT_CFG4 as 0x40 ("Reserved for serial > ROM"), and fixing BOOT_CFG1 to 0x30, but it was only a try. In fact, we > need to change BMODE from internal to serial, and I do not see a way in > the "official" documentation. > It doesn't help that all of this is undocumented :), but reverse- engineering the bmode command The "bmode usb" command sets gpr9 to 1, which isn't used for anything else, so something like this will work: diff --git a/arch/arm/imx-common/spl.c b/arch/arm/imx-common/spl.c index 28217d2..54f22e6 100644 --- a/arch/arm/imx-common/spl.c +++ b/arch/arm/imx-common/spl.c @@ -26,8 +26,10 @@ u32 spl_boot_device(void) * Check for BMODE if serial downloader is enabled * BOOT_MODE - see IMX6DQRM Table 8-1 */ - if ((bmode >> 24) == 0x01) /* Serial Downloader */ + if (((bmode >> 24) == 0x01) /* Serial Downloader */ + || (gpr10_boot && (1 == reg))) return BOOT_DEVICE_UART; AFAIK, there isn't any other way to get a value of 1 into GPR9, so the test is safe. Secondarily, since the low four bits are discarded in the switch(), this prevents an almost-always-wrong interpretation of 1 as OneNAND/NOR (I think there are very few if any i.MX6 boards using OneNAND or NOR for boot). Regards, Eric