[U-Boot] [PATCH v3 2/2] imx_common: detect USB serial downloader reliably

[Stefan Agner]

On September 18, 2017 8:05:43 AM PDT, Stefano Babic <sbabic at denx.de> wrote:
>Hi Stefan,
>
>On 14/09/2017 07:24, Eric Nelson wrote:
>> Hi Stefan,
>> 
>> Thanks for this patch.
>> 
>> On 09/13/2017 02:29 PM, Stefan Agner wrote:
>>> From: Stefan Agner <stefan.agner at toradex.com>
>>>
>>> The current mechanism using SCR/GPR registers work well when
>>> the serial downloader boot mode has been selected explicitly
>>> (either via boot mode pins or using bmode command). However,
>>> in case the system entered boot ROM due to unbootable primary
>>> boot devices (e.g. empty eMMC), the SPL fails to detect that
>>> it has been downloaded through serial loader and tries to
>>> continue booting from eMMC:
>>>    Trying to boot from MMC1
>>>    mmc_load_image_raw_sector: mmc block read error
>>>    SPL: failed to boot from all boot devices
>>>    ### ERROR ### Please RESET the board ###
>>>
>>> The only known way to reliably detect USB serial downloader
>>> is by checking the USB PHY receiver block power state...
>>>
>>> Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
>>> Acked-by: Marcel Ziswiler <marcel.ziswiler at toradex.com>
>>> Tested-by: Fabio Estevam <fabio.estevam at nxp.com>
>>> ---
>>>
>>> Changes in v4:
>>> - Rename macro to is_usbotg_phy_active()
>>>
>>> Changes in v3:
>>> - Fix spelling and grammar
>>>
>>> Changes in v2:
>>> - Add comment that we infer boot ROM behavior from USB PHY state
>>>
>>>   arch/arm/mach-imx/spl.c | 12 ++++++++++++
>>>   1 file changed, 12 insertions(+)
>>>
>>> diff --git a/arch/arm/mach-imx/spl.c b/arch/arm/mach-imx/spl.c
>>> index 258578ac25..534cc6504d 100644
>>> --- a/arch/arm/mach-imx/spl.c
>>> +++ b/arch/arm/mach-imx/spl.c
>>> @@ -31,6 +31,18 @@ u32 spl_boot_device(void)
>>>       if (((bmode >> 24) & 0x03) == 0x01) /* Serial Downloader */
>>>           return BOOT_DEVICE_BOARD;
>>>   +    /*
>>> +     * The above method does not detect that the boot ROM used
>>> +     * serial downloader in case the boot ROM decided to use the
>>> +     * serial downloader as a fall back (primary boot source
>failed).
>>> +     *
>>> +     * Infer that the boot ROM used the USB serial downloader by
>>> +     * checking whether the USB PHY is currently active... This
>>> +     * assumes that SPL did not (yet) initialize the USB PHY...
>>> +     */
>>> +    if (is_otgusb_phy_active())
>
>This is "otgusb", but in sys_proto.h is "usbotg".
>
>Can I fix it myself as "usbotg" by merging ?

Good point, wonder why I did not notice, I usually build it again. Sure go ahead.

--
Stefan

>
>Best regards,
>Stefano
>
>>> +        return BOOT_DEVICE_BOARD;
>>> +
>>>       /* BOOT_CFG1[7:4] - see IMX6DQRM Table 8-8 */
>>>       switch ((reg & IMX6_BMODE_MASK) >> IMX6_BMODE_SHIFT) {
>>>        /* EIM: See 8.5.1, Table 8-9 */
>>>
>> 
>> Reviewed-by: Eric Nelson <eric at nelint.com>

-- 
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