[PATCH 4/4] arm/dts: am33xx: Add CPSW and MDIO module nodes for AM33XX
b-cousson at ti.com
Thu Nov 1 05:28:47 EDT 2012
On 11/1/2012 8:45 AM, Richard Cochran wrote:
> On Wed, Oct 31, 2012 at 04:17:27PM +0100, Benoit Cousson wrote:
>>> + compatible = "ti,cpsw";
>>> + ti,hwmods = "cpgmac0";
>>> + cpdma_channels = <8>;
>>> + host_port_no = <0>;
>>> + cpdma_reg_ofs = <0x800>;
>>> + cpdma_sram_ofs = <0xa00>;
>>> + ale_reg_ofs = <0xd00>;
>>> + ale_entries = <1024>;
>>> + host_port_reg_ofs = <0x108>;
>>> + hw_stats_reg_ofs = <0x900>;
>>> + bd_ram_ofs = <0x2000>;
>>> + bd_ram_size = <0x2000>;
>>> + no_bd_ram = <0>;
>>> + rx_descs = <64>;
>>> + mac_control = <0x20>;
>> Do you have to store all these data in the DTS? Cannot it be in the driver?
>> Do you expect to have several instance of the same IP with different
>> parameters here?
> As I understand it, there are only two different layouts for the CPSW,
> the one in the dm814x and the one in the am335x. So I think it would
> work to put only the version register offet in the DT, and the let the
> driver figure out the rest from there.
Yes, that's indeed better. We did that for other IPs already (GPIO, I2C...)
> But if TI is planning on reordering the registers with each new
> silicon revision, again and again, then it might make sense to keep
> the offsets in the DT.
Yeah, let's assume they will do a better job in the future.
All these offset registers information does belong to the driver, and
even if the HW change a lot, I still rather hide that in the driver.
It will always be cleaner, most efficient, and will reduce the size if
> [ I really wonder why the hardware people think that reshuffling the
> register layout constitutes an improvement. ]
I've been wondering that for ten years :-(
I'm always hoping it will be better some day.
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