Re: [PATCH 0/2] readline_simple: return -1 if getc fails

From: Oleksij Rempel <linux@rempel-privat.de>
To: "Gaël PORTAY" <gael.portay@savoirfairelinux.com>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH 0/2] readline_simple: return -1 if getc fails
Date: Wed, 9 Aug 2017 21:41:36 +0200	[thread overview]
Message-ID: <f5129a96-709e-da38-0453-78e424a3dc5d@rempel-privat.de> (raw)
In-Reply-To: <20170809185853.lvlar7vyder6supt@gportay>

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Am 09.08.2017 um 20:58 schrieb Gaël PORTAY:
> Hi,
> 
> On Wed, Aug 09, 2017 at 08:05:57AM +0200, Oleksij Rempel wrote:
>> Am 09.08.2017 um 06:13 schrieb Gaël PORTAY:
>>> Dear maintainers,
>>>
>>> I came accross this issue when I was trying to add support for a new MIPS
>>> board.
>>
>> Just out of curiosity, what MIPS board are you working on? If it is not
>> a secret :)
>>
> 
> I am working on VoCore2[1]; it is a board based on a mediatek mt7628 CPU.
> 
> I am doing this to learn myself how works barebox 
> 
> Offtopic: For now it is booting on a really really old version of u-boot. I am
> able de boot barebox from u-boot. I had to hack the mips_disable_interrupts to
> remove the reset of flag ERL in CP0; but I don't know why yet. This flag is
> supposed to be set when CPU reboots; but because I am running barebox from a the
> command go of u-boot, this flag is unset.
> 
> Are you able to re-run barebox from barebox on your MIPS board?

Yes, usually i prefer to make a binaries wich are able to start from
RAM, Jtag and Flash. Currently we test if it is running from spi flash
adn skip most of the low level init:
https://github.com/olerem/barebox/blob/ar9344-2017.08.01.1/arch/mips/boards/tplink-mr3020/include/board/board_pbl_start.h#L29

On this board i decided to use SRAM for low level init testing:
https://github.com/olerem/barebox/blob/ar9344-2017.08.01.1/arch/mips/boards/tplink-wdr4300/include/board/board_pbl_start.h#L38

> 	.macro	mips_disable_interrupts
> 	.set	push
> 	.set	noreorder
> 	mfc0	k0, CP0_STATUS
> -	li	k1, ~(ST0_ERL | ST0_IE)
> +	li	k1, ~ST0_IE
> 	and	k0, k1
> 	mtc0	k0, CP0_STATUS
> 	.set	pop
> 	.endm
> 
> For now, I have splitted mips_disable_interrupts into two macros. The second
> macro mips_reset_error_level checks if the ERL flag is armed before resetting it
> to 0.
> 
> 	.macro	mips_reset_error_level
> 	.set	push
> 	.set	noreorder
> 	mfc0	k0, CP0_STATUS
> 	li	k1, ST0_ERL
> 	and	k1, k0
> 	bne	k1, zero, 1f
> 	li	k1, ~(ST0_ERL)
> 	and	k0, k1
> 	mtc0	k0, CP0_STATUS
> 1:	.set	pop
> 	.endm
> 
> But I don't know if this is the right thing to do.
>  
> [1]: https://www.indiegogo.com/projects/vocore2-4-coin-sized-linux-computer-with-wifi#/
> 

-- 
Regards,
Oleksij

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