On pon, 2014-06-09 at 09:04 -0700, Doug Anderson wrote: > Krzystof, > > On Mon, Jun 9, 2014 at 3:16 AM, Krzysztof Kozlowski > <k.kozlowski@xxxxxxxxxxx> wrote: > > On pon, 2014-06-09 at 11:37 +0200, Javier Martinez Canillas wrote: > >> MAX77802 is a PMIC that contains 10 high efficiency Buck regulators, > >> 32 Low-dropout (LDO) regulators, two 32kHz buffered clock outputs, > >> a Real-Time-Clock (RTC) and a I2C interface to program the individual > >> regulators, clocks and the RTC. > >> > >> This series are based on drivers added by Simon Glass to the Chrome OS > >> kernel and adds support for the Maxim 77802 Power Management IC, their > >> regulators, clocks, RTC and I2C interface. It is composed of patches: > >> > >> [PATCH 1/5] mfd: Add driver for Maxim 77802 Power Management IC > >> [PATCH 2/5] regulator: Add driver for Maxim 77802 PMIC regulators > >> [PATCH 3/5] clk: Add driver for Maxim 77802 PMIC clocks > >> [PATCH 4/5] rtc: Add driver for Maxim 77802 PMIC Real-Time-Clock > >> [PATCH 5/5] ARM: dts: Add max77802 device node for exynos5420-peach-pit > >> > >> Patches 1-4 add support for the different devices and Patch 5 enables > >> the MAX77802 PMIC on the Exynos5420 based Peach pit board. > > > > > > Hi, > > > > The main mfd, mfd irq, clk and rtc drivers look very similar to max77686 > > drivers. I haven't checked other Maxim drivers but I think there will be > > a lot of similarities with them also. It is almost common for Maxim > > chipsets to share components between each other. > > > > I think there is no need in duplicating all that stuff once again in new > > driver for another Maxim-almost-the-same-as-others-XYZ chipset. Just > > merge it with max77686 (or other better candidate). > > > > The only difference is in regulator driver. I am not sure whether this > > is a result of differences in chip or differences in driver design. > > Yes, we thought the same thing when we added support for the max77802 > in the ChromeOS tree. Unfortunately it didn't work out half as well > as we thought it would. When Javier was asking advice about sending > things upstream we suggested that perhaps he should split the two up. > > > You can see the result of the combined driver the ChromeOS tree (the > code there is older, probably misnamed as max77xxx, and doesn't have > the proper clock pieces, but you can get the gist): > > https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.8/drivers/regulator/max77xxx-regulator.c > https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.8/drivers/rtc/rtc-max77xxx.c > > > Specific problems that made it ugly to have a combined driver: > > * The RTC has many subtle differences between the 77686 and 77802. > They expanded it to handle a 200 year timeframe instead of 100 and > that meant that they had to shuffle the bits around everywhere. They > also moved it to have the same i2c address as the main PMIC so all > addresses are different (see max77686_map in the RTC link above). The difference in RTC registers seems the biggest but it can be solved in readable manner. I see other differences but there aren't many. It just hurts seeing so much code duplication: $ sed -e 's/max77686/max77802/g' -e 's/MAX77686/MAX77802/g' \ -i drivers/rtc/rtc-max77686.c $ diff -ubB drivers/rtc/rtc-max77686.c drivers/rtc/rtc-max77802.c The combined RTC driver from ChromeOS seems fine to me... but I do not insist. > * The regulator itself has similar concepts between the two, but the > list of bucks / ldos and how they behave is quite different. Trying > to understand the complex tables in > <https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.8/drivers/regulator/max77xxx-regulator.c> > was not easy. > > > If we really need to write a single driver it certainly can be done, > but please look at the above to be sure this is what you want. Sure, I don't stick to the idea of one merged driver where this increases code size and complexity. I see your point that merging regulator drivers won't bring benefits but please: $ sed -e 's/max77686/max77802/g' -e 's/MAX77686/MAX77802/g' \ -i drivers/clk/clk-max77686.c $ diff -ubB drivers/clk/clk-max77686.c drivers/clk/clk-max77802.c The difference in number of clocks (2 vs 3) is not an obstacle here. The same applies to main MFD driver and IRQ code. However MAX77686 doesn't use regmap_irq_chip so it needs changes before merging the IRQ code into one piece. Best regards, Krzysztof > > NOTE: it's possible that things could be more sane with more driver > redesign, possibly making things more data driven. The thing that > would be really nice to do would be to avoid all of the crazy > "regulator_zzz_desc_zzz" macros, maybe? I'd have to actually try > doing it to be sure it's cleaner, though... > > > -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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