Re: [PATCH] usb: bootm: Drop old USB-device-removal code

[Mattijs Korpershoek <mkorpershoek@baylibre.com>]

Hi Simon,

Thank you for the patch.

On ven., juil. 26, 2024 at 06:36, Simon Glass <sjg@chromium.org> wrote:

> USB is stopped using driver model now, in dm_remove_devices_flags() in
> announce_and_cleanup() at the top of this file.
>
> The usb_stop() call actually unbinds devices.
>
> When a USB device is unbound, it causes any bootflows attached to it to
> be removed, via a call to bootdev_clear_bootflows() from
> bootdev_pre_unbind(). This obviously makes it impossible to boot the
> bootflow.
>
> However, when booting a bootflow that relies on USB, usb_stop() is
> called, which unbinds the device. At that point any information
> attached to the bootflow is dropped.
>
> This is quite risky since the contents of freed memory are not
> guaranteed to remain unchanged. Depending on what other options are
> done before boot, a hard-to-find bug may crop up.
>
> Drop the call to this old function.
>
> Leave the netconsole call there, since this needs conversion to
> driver model.
>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> Suggested-by: Shantur Rathore <i@shantur.com>

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

> ---
> The original patch was here:
> https://patchwork.ozlabs.org/project/uboot/patch/
> 20231119121144.v5.5.If206027372f73ce32480223e5626f4b944e281b7@changeid/
>
>  boot/bootm.c | 12 ------------
>  1 file changed, 12 deletions(-)
>
> diff --git a/boot/bootm.c b/boot/bootm.c
> index 376d63aafc9..480f8e6a0e6 100644
> --- a/boot/bootm.c
> +++ b/boot/bootm.c
> @@ -740,18 +740,6 @@ ulong bootm_disable_interrupts(void)
>  	eth_halt();
>  #endif
>  
> -#if defined(CONFIG_CMD_USB)
> -	/*
> -	 * turn off USB to prevent the host controller from writing to the
> -	 * SDRAM while Linux is booting. This could happen (at least for OHCI
> -	 * controller), because the HCCA (Host Controller Communication Area)
> -	 * lies within the SDRAM and the host controller writes continously to
> -	 * this area (as busmaster!). The HccaFrameNumber is for example
> -	 * updated every 1 ms within the HCCA structure in SDRAM! For more
> -	 * details see the OpenHCI specification.
> -	 */
> -	usb_stop();
> -#endif
>  	return iflag;
>  }
>  
> -- 
> 2.34.1