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 11:20:25 +0100 [thread overview]
Message-ID: <4B728869.1090404@grandegger.com> (raw)
In-Reply-To: <4B72794A.9010805@grandegger.com>
Wolfgang Grandegger wrote:
> 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.
That said, I think there is consensus that it does not make sense, and
it's even not possible, to provide a kernel image which runs on both,
the 8xx and the mpc512x. Therefore, there is also no need for sharing
this driver at run time. Compile time selection would allow a more
elegant and transparent implementation. Would that be an acceptable
solution?
Wolfgang.
next prev parent reply other threads:[~2010-02-10 10:21 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
2010-02-10 10:20 ` Wolfgang Grandegger [this message]
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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