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From: Wolfgang Grandegger <wg@grandegger•com>
To: David Miller <davem@davemloft•net>
Cc: agust@denx•de, netdev@vger•kernel.org, dzu@denx•de, wd@denx•de,
	jcrigby@gmail•com, kosmo@semihalf•com, linuxppc-dev@ozlabs•org,
	grant.likely@secretlab•ca
Subject: Re: [net-next-2.6 PATCH 2/3] fs_enet: Add support for MPC512x to fs_enet driver
Date: Wed, 10 Feb 2010 10:15:54 +0100	[thread overview]
Message-ID: <4B72794A.9010805@grandegger.com> (raw)
In-Reply-To: <20100209.121356.216640014.davem@davemloft.net>

Hi David,

David Miller wrote:
> From: Anatolij Gustschin <agust@denx•de>
> Date: Tue, 9 Feb 2010 15:23:17 +0100
> 
>> In my understanding, in the ESP scsi driver the set of defines for
>> the register offsets is common for all chip drivers. The chip driver
>> methods for register access translate the offsets because the
>> registers on some chips are at different intervals (4-byte, 1-byte,
>> 16-byte for mac_esp.c). But the register order is the same for
>> different chips.
>>
>> In our case non only the register order is not the same for 8xx
>> FEC and 5121 FEC, but there are also other differences, different
>> reserved areas between several registers, some registers are
>> available only on 8xx and some only on 5121.
> 
> That only means you would need to use a table based register address
> translation scheme, rather than a simple calculation.  Something
> like:
> 
> static unsigned int chip_xxx_table[] =
> {
> 	[GENERIC_REG_FOO]	 = CHIP_XXX_FOO,
> 	...
> };
> 
> static u32 chip_xxx_read_reg(struct chip *p, unsigned int reg)
> {
> 	unsigned int reg_off = chip_xxx_table[reg];
> 
> 	return readl(p->regs + reg_off);
> }
> 
> And this table can have special tokens in entries for
> registers which do not exist on a chip, so you can trap
> attempted access to them in these read/write handlers.

Yes, that could be done, but to honest, I do not see any improvement in
respect to the previous patch where the register offset were defined via
pointers within a structure.

> Please stop looking for excuses to fork this driver, a
> unified driver I think can be done cleanly.

Other people suggested to fork the driver because it's getting too ugly.

Wolfgang.

  reply	other threads:[~2010-02-10  9:17 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-21  2:13 [net-next-2.6 PATCH 0/3] Support for MPC512x FEC Anatolij Gustschin
2010-01-21  2:13 ` [net-next-2.6 PATCH 1/3] fs_enet: use dev_xxx instead of printk Anatolij Gustschin
2010-01-21 16:43   ` Grant Likely
2010-01-21  2:13 ` [net-next-2.6 PATCH 2/3] fs_enet: Add support for MPC512x to fs_enet driver Anatolij Gustschin
2010-01-21  9:22   ` David Miller
2010-01-21  9:33     ` Anatolij Gustschin
2010-01-21 15:25     ` Wolfgang Grandegger
2010-01-22  2:03       ` David Miller
2010-01-22  9:35         ` Wolfgang Grandegger
2010-02-09 14:23         ` Anatolij Gustschin
2010-02-09 20:13           ` David Miller
2010-02-10  9:15             ` Wolfgang Grandegger [this message]
2010-02-10 10:20               ` Wolfgang Grandegger
2010-02-10 14:28                 ` Grant Likely
2010-01-23  9:23       ` Arnd Bergmann
2010-01-24 14:40         ` Wolfgang Grandegger
2010-01-24 16:41           ` Wolfgang Denk
2010-01-27  2:06             ` Arnd Bergmann
2010-01-27  8:13               ` Wolfgang Grandegger
2010-01-21 20:15   ` Wolfgang Grandegger
2010-01-21  2:13 ` [net-next-2.6 PATCH 3/3] fs_enet: Add FEC TX Alignment workaround for MPC5121 Anatolij Gustschin
2010-01-21 16:49   ` Grant Likely

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