From: zhichang.yuan02@gmail.com (zhichang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH V2 4/4] ARM64 LPC: support earlycon for UART connected to LPC
Date: Thu, 8 Sep 2016 18:04:31 +0800 [thread overview]
Message-ID: <57D137AF.9070306@gmail.com> (raw)
In-Reply-To: <4291379.IHAA72aKCk@wuerfel>
Hi, Arnd,
On 2016?09?07? 22:52, Arnd Bergmann wrote:
> On Wednesday, September 7, 2016 9:33:53 PM CEST Zhichang Yuan wrote:
>> From: "zhichang.yuan" <yuanzhichang@hisilicon.com>
>>
>> This patch support the earlycon for UART connected to LPC on Hip06.
>> This patch is depended on the LPC driver.
>>
>> Signed-off-by: zhichang.yuan <yuanzhichang@hisilicon.com>
>>
>
> I'm skeptical about this too. Is this just needed because the 8250
> earlycon support comes before the lpc bus initialization?
I think you wonder why early_serial8250_setup can not be used direclty for this earlycon of LPC uart.
1. the earlycon kernel parameter format of LPC uart is different from 8250. something like that
"earlycon=hisilpcuart,mmio,0xa01b0000,0,0x2f8". You see, there is one more parameter after the baudrate.
Hip06 LPC uart need two base addresses for earlycon.
2. the IO type is mmio to introduce a memory base address to access LPC register file. But the real uart
IO type is UPIO_PORT. This is spcial...
3. Just as your guess, earlycon should be earlier than lpc initialization.
Best,
Zhichang
>
> Could we start the LPC driver earlier to work around that?
>
> Arnd
>
WARNING: multiple messages have this Message-ID (diff)
From: zhichang <zhichang.yuan02@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>, linux-arm-kernel@lists.infradead.org
Cc: Zhichang Yuan <yuanzhichang@hisilicon.com>,
linuxarm@huawei.com, linux-kernel@vger.kernel.org,
lorenzo.pieralisi@arm.com, minyard@acm.org,
benh@kernel.crashing.org, gabriele.paoloni@huawei.com,
john.garry@huawei.com, liviu.dudau@arm.com,
zourongrong@gmail.com
Subject: Re: [PATCH V2 4/4] ARM64 LPC: support earlycon for UART connected to LPC
Date: Thu, 8 Sep 2016 18:04:31 +0800 [thread overview]
Message-ID: <57D137AF.9070306@gmail.com> (raw)
In-Reply-To: <4291379.IHAA72aKCk@wuerfel>
Hi, Arnd,
On 2016年09月07日 22:52, Arnd Bergmann wrote:
> On Wednesday, September 7, 2016 9:33:53 PM CEST Zhichang Yuan wrote:
>> From: "zhichang.yuan" <yuanzhichang@hisilicon.com>
>>
>> This patch support the earlycon for UART connected to LPC on Hip06.
>> This patch is depended on the LPC driver.
>>
>> Signed-off-by: zhichang.yuan <yuanzhichang@hisilicon.com>
>>
>
> I'm skeptical about this too. Is this just needed because the 8250
> earlycon support comes before the lpc bus initialization?
I think you wonder why early_serial8250_setup can not be used direclty for this earlycon of LPC uart.
1. the earlycon kernel parameter format of LPC uart is different from 8250. something like that
"earlycon=hisilpcuart,mmio,0xa01b0000,0,0x2f8". You see, there is one more parameter after the baudrate.
Hip06 LPC uart need two base addresses for earlycon.
2. the IO type is mmio to introduce a memory base address to access LPC register file. But the real uart
IO type is UPIO_PORT. This is spcial...
3. Just as your guess, earlycon should be earlier than lpc initialization.
Best,
Zhichang
>
> Could we start the LPC driver earlier to work around that?
>
> Arnd
>
next prev parent reply other threads:[~2016-09-08 10:04 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-07 13:33 [PATCH V2 0/4] ARM64 LPC: legacy ISA I/O support Zhichang Yuan
2016-09-07 13:33 ` Zhichang Yuan
2016-09-07 13:33 ` [PATCH V2 1/4] ARM64 LPC: Indirect ISA port IO introduced Zhichang Yuan
2016-09-07 13:33 ` Zhichang Yuan
2016-09-07 15:06 ` Arnd Bergmann
2016-09-07 15:06 ` Arnd Bergmann
2016-09-08 7:45 ` zhichang.yuan
2016-09-08 7:45 ` zhichang.yuan
2016-09-08 7:45 ` zhichang.yuan
2016-09-08 13:23 ` Arnd Bergmann
2016-09-08 13:23 ` Arnd Bergmann
2016-09-13 6:08 ` zhichang
2016-09-13 6:08 ` zhichang
2016-09-07 15:21 ` kbuild test robot
2016-09-07 15:21 ` kbuild test robot
2016-09-07 13:33 ` [PATCH V2 2/4] ARM64 LPC: LPC driver implementation on Hip06 Zhichang Yuan
2016-09-07 13:33 ` Zhichang Yuan
2016-09-07 15:27 ` Arnd Bergmann
2016-09-07 15:27 ` Arnd Bergmann
2016-09-08 8:06 ` zhichang.yuan
2016-09-08 8:06 ` zhichang.yuan
2016-09-08 10:00 ` Arnd Bergmann
2016-09-08 10:00 ` Arnd Bergmann
2016-09-13 6:31 ` zhichang
2016-09-13 6:31 ` zhichang
2016-09-14 12:34 ` Arnd Bergmann
2016-09-14 12:34 ` Arnd Bergmann
2016-09-07 17:51 ` kbuild test robot
2016-09-07 17:51 ` kbuild test robot
2016-09-07 13:33 ` [PATCH V2 3/4] ARM64 LPC: support serial based on low-pin-count Zhichang Yuan
2016-09-07 13:33 ` Zhichang Yuan
2016-09-07 14:50 ` Arnd Bergmann
2016-09-07 14:50 ` Arnd Bergmann
2016-09-08 9:51 ` zhichang
2016-09-08 9:51 ` zhichang
2016-09-08 9:58 ` Arnd Bergmann
2016-09-08 9:58 ` Arnd Bergmann
2016-09-14 11:48 ` zhichang.yuan
2016-09-14 11:48 ` zhichang.yuan
2016-09-14 12:07 ` Arnd Bergmann
2016-09-14 12:07 ` Arnd Bergmann
2016-09-07 13:33 ` [PATCH V2 4/4] ARM64 LPC: support earlycon for UART connected to LPC Zhichang Yuan
2016-09-07 13:33 ` Zhichang Yuan
2016-09-07 14:52 ` Arnd Bergmann
2016-09-07 14:52 ` Arnd Bergmann
2016-09-08 10:04 ` zhichang [this message]
2016-09-08 10:04 ` zhichang
2016-09-08 11:04 ` Arnd Bergmann
2016-09-08 11:04 ` Arnd Bergmann
2016-09-14 11:26 ` zhichang
2016-09-14 11:26 ` zhichang
2016-09-14 12:36 ` Arnd Bergmann
2016-09-14 12:36 ` Arnd Bergmann
2016-09-08 9:26 ` kbuild test robot
2016-09-08 9:26 ` kbuild test robot
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