[U-Boot] [PATCH V2 3/4] common: introduce board_preboot_os hook

Stefano Babic
2014-11-05T12:32:15Z

Hi Nikita,

On 29/10/2014 16:56, Nikita Kiryanov wrote:
> Introduce board specific function board_preboot_os() to allow for board
> specific config before we boot.
>
> Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
> Cc: Igor Grinberg <grinberg@compulab.co.il>
> Cc: Stefano Babic <sbabic@denx.de>
> Cc: Tom Rini <trini@ti.com>
> Cc: Jeroen Hofstee <jeroen@myspectrum.nl>
> Cc: Otavio Salvador <otavio@ossystems.com.br>
> ---
> Changes in V2:
> - Added board_preboot_os to bootm.h
> - Split cm_fx6 stuff into a separate patch
>
> common/bootm_os.c | 7 +++++++
> include/bootm.h | 1 +
> 2 files changed, 8 insertions(+)
>

There is something that does not convince me. Really, the general
statement should be to turn all devices off before booting the kernel,
because this is what Linux expects. That said, this could be later
solved with dm, because we will can iterate through all drivers and call
a shutdown function.

Currently, "preboot" functions are turning off the hardware, so the name
is already misleading. And I see that arch_preboot_os() was also
convinced (because it is weak) to become a board_preboot, for example
here: board/renesas/koelsch/koelsch.c (and in other renesas
implementation, too).

I have some concerns adding a new weak function, that enables some
further hooks inside board code. I find it not well scalable.
In your case, you need such as sata_shutdown(), and it should be
responsibility of the general sata code to call something specific for
the board, if necessary.

In current code, bootm_disable_interrupts() calls also usb_stop() and
eth_halt(), - nothing to do with the name of the function. IMHO it
should be better to move the code to shutdown interface inside
boot_selected_os(), or having a common function "disable_hardware()"
that calls usb_stop(), eth_halt() and then, why not, a sata_stop().

There is also in arch/arm/imx-common/cpu.c a derived implementation for
arch_preboot_os(). Really it has nothing to do with arch, as I can see:
it shuts down only the IPU. But it is another hook, and IMHO it is
better stopping sata here as adding a hidden callback.

Best regards,
Stefano Babic

> diff --git a/common/bootm_os.c b/common/bootm_os.c
> index 5be4467..95cd657 100644
> --- a/common/bootm_os.c
> +++ b/common/bootm_os.c
> @@ -442,10 +442,17 @@ __weak void arch_preboot_os(void)
> /* please define platform specific arch_preboot_os() */
> }
>
> +/* Allow for board specific config before we boot */
> +__weak void board_preboot_os(void)
> +{
> + /* please define board specific board_preboot_os() */
> +}
> +
> int boot_selected_os(int argc, char * const argv[], int state,
> bootm_headers_t *images, boot_os_fn *boot_fn)
> {
> arch_preboot_os();
> + board_preboot_os();
> boot_fn(state, argc, argv, images);
>
> /* Stand-alone may return when 'autostart' is 'no' */
> diff --git a/include/bootm.h b/include/bootm.h
> index b3d1a62..7a57264 100644
> --- a/include/bootm.h
> +++ b/include/bootm.h
> @@ -55,5 +55,6 @@ int do_bootm_states(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
> int states, bootm_headers_t *images, int boot_progress);
>
> void arch_preboot_os(void);
> +void board_preboot_os(void);
>
> #endif
>

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