Hi Protsenko, > On Fri, 19 Nov 2021 at 10:54, Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx> wrote: > > > > On 18/11/2021 20:59, Sam Protsenko wrote: > > > On Tue, 16 Nov 2021 at 11:32, Krzysztof Kozlowski > > > <krzysztof.kozlowski@xxxxxxxxxxxxx> wrote: > > >> > > >> On 16/11/2021 02:12, Chanho Park wrote: > > >>>> With this patch the Exynos850 HSI2C becomes functional. The only > > >>>> nit-pick from my side (just a food for thought): do we want to > > >>>> configure USI related config inside of particular drivers (SPI, > > >>>> I2C, UART)? Or it would be better design to implement some > > >>>> platform driver for that, so we can choose USI configuration > > >>>> (SPI/I2C/UART) in device tree? I think this series is good to be > > >>>> merged as is, but we should probably consider all upsides and downsides of each option, for the > future work. > > >>> > > >>> I'm also considering how to support this USI configuration gracefully. > > >>> Current version of USI is v2 which means there is a v1 version as well. It might be a non- > upstream SoC so we don't need to consider it so far. > > >>> But, there is a possibility that the USI hw version can be bumped for future SoCs. > > >>> > > >>> As you probably know, earlier version of the product kernel has a USI SoC driver[1] and it was > designed to be configured the USI settings by device tree. > > >>> > > >>> Option1) Make a USI driver under soc/samsung/ like [1]. > > >>> Option2) Use more generic driver such as "reset driver"? This might be required to extend the > reset core driver. > > >>> Option3) Each USI driver(uart/i2c/spi) has its own USI configurations respectively and expose > some configurations which can be variable as device tree. > > >>> > > >>> [1]: > > >>> https://protect2.fireeye.com/v1/url?k=b290a67b-ed0b9f6a-b2912d34-0 > > >>> cc47a31cdbc-ceadd8e62313162a&q=1&e=317825c0-3fac-46ad-9b4e-f93de42 > > >>> ad5ba&u=https%3A%2F%2Fgithub.com%2Fianmacd%2Fd2s%2Fblob%2Fmaster%2 > > >>> Fdrivers%2Fsoc%2Fsamsung%2Fusi_v2.c > > >> > > >> I don't have user manuals, so all my knowledge here is based on > > >> Exynos9825 vendor source code, therefore it is quite limited. In > > >> devicetree the USI devices have their own nodes - but does it mean > > >> it's separate SFR range dedicated to USI? Looks like that, > > >> especially that address space is just for one register (4 bytes). > > >> > > >> In such case having separate dedicated driver makes sense and you > > >> would only have to care about driver ordering (e.g. via device links or phandles). > > >> > > >> Option 2 looks interesting - reusing reset framework to set proper > > >> USI mode, however this looks more like a hack. As you said Chanho, > > >> if there is a USI version 3, this reset framework might not be sufficient. > > >> > > >> In option 3 each driver (UART/I2C/SPI) would need to receive second > > >> IO range and toggle some registers, which could be done via shared > > >> function. If USI v3 is coming, all such drivers could get more complicated. > > >> > > >> I think option 1 is the cleanest and extendable in future. It's > > >> easy to add usi-v3 or whatever without modifying the UART/I2C/SPI > > >> drivers. It also nicely encapsulates USI-related stuff in separate > > >> driver. Probe ordering should not be a problem now. > > >> > > >> But as I said, I don't have even the big picture here, so I rely on > > >> your opinions more. > > >> > > > > > > Hi Krzysztof, > > > > > > Can you please let me know if you're going to apply this series as > > > is, or if you want me to submit USIv2 driver first, and then rework > > > this patch on top of it? I'm working on some HSI2C related patches > > > right now, and thus it'd nice to know about your decision on this > > > series beforehand, as some of my patches (like bindings doc patches) > > > might depend on it. Basically I'd like to base my patches on the > > > proper baseline, so we don't have to rebase those later. > > > > This set won't go via my tree anyway, but I am against it. David > > pointed out that his USIv1 is a little bit different and embedding in > > each of I2C/UART/SPI drivers the logic of controlling USIv1 and USIv2 > > looks too big. The solution with a dedicated driver looks to me more > > flexible and encapsulated/cleaner. > > > > Therefore after the discussions I am against this solution, so a > > soft-NAK from my side. > > > > Hi Jaewon, > > I'm going to submit USI driver soon, and also some more HSI2C patches. > Do you mind if I rework your patches to rely on USI drver (instead of modifying System Register in > HSI2C driver), and include those in my patch series? Of course, I'll preserve your authorship. Just > think that would be easier and faster this way. > > Thanks! > I'm glad you're working on a USI driver. You can use my patchset. > > > > Best regards, > > Krzysztof Thanks Jaewon Kim
