Message-ID: <20080508130833.GA25971@roarinelk.homelinux.net>
Date:	Thu, 8 May 2008 15:08:33 +0200
From:	Manuel Lauss <mano@...rinelk.homelinux.net>
To:	Sergei Shtylyov <sshtylyov@...mvista.com>
Cc:	linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] Alchemy: db1200/pb1200: register mmc platform
	device and board specific functions

Hi Sergei,

On Thu, May 08, 2008 at 04:41:32PM +0400, Sergei Shtylyov wrote:
>> diff --git a/arch/mips/au1000/common/platform.c 
>> b/arch/mips/au1000/common/platform.c
>> index 31d2a22..08a5900 100644
>> --- a/arch/mips/au1000/common/platform.c
>> +++ b/arch/mips/au1000/common/platform.c
>> -
>> -static struct platform_device au1xxx_mmc_device = {
>> -	.name = "au1xxx-mmc",
>> -	.id = 0,
>> -	.dev = {
>> -		.dma_mask               = &au1xxx_mmc_dmamask,
>> -		.coherent_dma_mask      = 0xffffffff,
>> -	},
>> -	.num_resources  = ARRAY_SIZE(au1xxx_mmc_resources),
>> -	.resource       = au1xxx_mmc_resources,
>> -};
>>  #endif /* #ifdef CONFIG_SOC_AU1200 */
>
>    What board-specific was here?

Nothing in here per se, but a) I don't like this file, it registers
stuff some boards don't need/want,  b) this part is only interesting
for pb1200 board anyway. I moved it to the pb1200 platform.c because
of the function pointers for au1xmmc platdata.


>>  static struct platform_device au1x00_pcmcia_device = {
>> diff --git a/arch/mips/au1000/pb1200/platform.c 
>> b/arch/mips/au1000/pb1200/platform.c
>> index 5930110..bee2bf7 100644
>> --- a/arch/mips/au1000/pb1200/platform.c
>> +++ b/arch/mips/au1000/pb1200/platform.c
>> @@ -20,8 +20,17 @@
>>   #include <linux/init.h>
>>  #include <linux/platform_device.h>
>> +#include <linux/mmc/host.h>
>>   #include <asm/mach-au1x00/au1xxx.h>
>> +#include <asm/mach-au1x00/au1xxx_dbdma.h>
>> +#include <asm/mach-au1x00/au1100_mmc.h>
>> +
>> +#if defined(CONFIG_MIPS_PB1200)
>> +#include <asm/mach-pb1x00/pb1200.h>
>> +#elif defined(CONFIG_MIPS_DB1200)
>> +#include <asm/mach-db1x00/db1200.h>
>> +#endif
>
> #include <asm/mach-au1x00/au1xxx.h> does all that already -- you don't need 
> to
> include the board specific headers one more time.  Drop this part please.

Done.  I originally put it in because of compile errors wrt. BCSR register.


>> +static int pb1200mmc_card_readonly(void *mmc_host)
>> +{
>> +	struct au1xmmc_host *host = mmc_priv((struct mmc_host *)mmc_host);
>
>    Insert new line after a declaration please.
>
>> +	return (bcsr->status & au1xmmc_card_table[host->id].wpstatus) ? 1 : 0;
>> +}
>> +
>> +static int pb1200mmc_card_inserted(void *mmc_host)
>> +{
>> +	struct au1xmmc_host *host = mmc_priv((struct mmc_host *)mmc_host);
>
>    The same here.

Done and done,


>> +	return (bcsr->sig_status & au1xmmc_card_table[host->id].bcsrstatus)
>> +		? 1 : 0;
>> +}
>> +
>> +static struct au1xmmc_platdata db1xmmcpd = {
>> +	.set_power	= pb1200mmc_set_power,
>> +	.card_inserted	= pb1200mmc_card_inserted,
>> +	.card_readonly	= pb1200mmc_card_readonly,
>> +	.cd_setup	= NULL,		/* use poll-timer in driver */
>
>    Function ptrs in the platform data?  That's something new -- though why 
>  not? :-)

Is this an accepted way of doing things in the kernel?  If not, I'm open to
suggestions! (I prefer this to globally-visible methods called by the
driver.  I like it when related things are neatly grouped together).


>> +};
>> +
>> +static u64 au1xxx_mmc_dmamask =  ~(u32)0;
>> +
>> +struct resource au1200sd0_res[] = {
>> +	[0] = {
>> +		.start	= CPHYSADDR(SD0_BASE),
>
>    Why not just use SD0_PHYS_ADDR?
>
>> +		.end	= CPHYSADDR(SD0_BASE) + 0x40,
>
>    You've missed "- 1" here. Though it's alos not clear why 0x40 and not 
> 0x3c (there's not register at 0x3c) or 0x80000 -- the range used according 
> to the memory map...

I'll add the whole 0x80000 range ;-)


>> +	[3] = {
>> +		.start	= DSCR_CMD0_SDMS_TX0,
>> +		.flags	= IORESOURCE_DMA,
>> +	},
>> +	[4] = {
>> +		.start	= DSCR_CMD0_SDMS_RX0,
>> +		.flags	= IORESOURCE_DMA,
>> +	},
>> +};
>
>    Humm. The other devices (like IDE) should also claim DMA resources...

It was a convenient way to pass DDMA IDs without having to use 
a lookup table in the driver ;-)


>> +
>> +static struct platform_device au1200_sd0_device = {
>> +	.name = "au1xxx-mmc",
>> +	.id = 0,	/* index into au1xmmc_card_table[] */
>> +	.dev = {
>> +		.dma_mask               = &au1xxx_mmc_dmamask,
>> +		.coherent_dma_mask      = 0xffffffff,
>> +		.platform_data		= &db1xmmcpd,
>
>    Can't we leave the MMC platform device where it is but define the 
> platform data structure per board with some starndard name? Since IMO it 
> doesn't make sense to move the platform device itself.

I like my device setup data in one file (preferably living in the board
subdir), but for mainline inclusion I can move it back to its original
place if you and others prefer so.


>> +	},
>> +	.num_resources  = ARRAY_SIZE(au1200sd0_res),
>> +	.resource       = au1200sd0_res,
>> +};
>> +
>> +#ifndef CONFIG_MIPS_DB1200
>
>    Wait, SD controller 1 is there regardless of the board, so should be 
> registerred regardless. If however the board doesn't have the necessary 
> resources to support the driver functionality, I think it can be indicated 
> by the board-level platform data, so that the driver could decide whether 
> it wants to support that controller or not.

Won't this cause problems if e.g. you are using PCMCIA (since SD1 pins are
muxed with pcmcia signals)? 
In any case, I just followed the original code, which also disabled the 2nd
controller for the db1200.


>> +struct resource au1200sd1_res[] = {
>> +	[0] = {
>> +		.start	= CPHYSADDR(SD1_BASE),
>> +		.end	= CPHYSADDR(SD1_BASE) + 0xff,
>
>    Why not 0x40 if the controllers are symmetric I wonder? I'd say it 
> should be 0x80000 even (and don't forget to sutract one ;-)...

I corrected this (and wrong resource numbering) locally.


Thanks for looking at it!
	Manuel Lauss
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