Am 29.04.19 um 11:40 schrieb Stefan Roese:
On 29.04.19 11:28, Weijie Gao wrote:
On Mon, 2019-04-29 at 07:08 +0200, Stefan Roese wrote:
On 28.04.19 11:38, Weijie Gao wrote:
The MediaTek MT7620 and MT7628 SoCs are different. Although they use the same memory controller, the lowlevel code (CPU PLL) and other peripherals they use are totally different. Which means they should use seperate mach directories.
s/seperate/separate
Currently the mach mt7620 contains only architecture code of MT7628. In case we add real arch support of MT7620 in the future, the arch should be renamed to mt7628, including both Kconfig files and directories. Other files affected are also modified.
Perhaps it would be possible to support both SoC's (MT7620 and MT7628/88) in one mach directory? Frankly I don't know the differences in detail, so its your call.
<snip>
Dear Stefan,
Thanks for pointing out the missing files.
Here is the summary of HW components needed by u-boot for MT7620 and MT7628:
L1 data cache: MT7620 can not lock it. MT7628 uses it to do DDR calibration. CPU frequency (PLL): MT7620 can change it. MT7628 can't. The PLL registers are different. DRAM controller: Near the same. MT7620 can't do calibration. MT7628 has extra PAD configurations.
These "devices / controllers" are handled in the mach-foo directory.
GPIO controller: Not the same IP core. SPI controller: Not the same IP core. Frame engine: Similar IP core, different generation. Built-in Ethernet switch: Not the same IP core.
And these controllers are handled in the drivers/foo directly. So any different IP core (between MT7620 and MT7628) has no effect to the mach directory.
Please don't misunderstand me. I absolutely agree that we need to differentiate between those two SoC's. So moving to CONFIG_SOC_MT7628 instead of SOC_MT7620 makes perfect sense. I only want to avoid the creation of another mach-foo directory, where code might be shared between both SoC's.
So I insist to split them into two mach directory.
I see. Okay, lets move forward then with your patch and lets finally decide if and what can be shared between those SoC's, once (if) support for the MT7620 arrives in mainline.
BTW: Do you plan on adding support for the MT7620 anytime soon?
I agree with Stefan, there is no need to create separate mach- directories. With the power of Kconfig and Kbuild you can easily handle multiple SoCs within one mach- directory, for instance look at mach-bmips or mach-mscc. Could you rather rename to mach-mediatek or mach-mtmips so that we would have the Kconfig symbols ARCH_MEDIATEK and SOC_MT7628 (plus SOC_MT7620 in the future)? Thanks.
BTW: it's good to see that another vendor in the MIPS area is stepping up to maintain its products in mainline ;)