Faiz On 1/10/19 1:57 AM, Rizvi, Mohammad Faiz Abbas wrote: > Hi Dan, Wolfgang, > > On 1/10/2019 1:14 PM, Wolfgang Grandegger wrote: >> Hello Dan, >> >> sorry for my late response on that topic... >> >> Am 09.01.19 um 21:58 schrieb Dan Murphy: >>> Wolfgang >>> >>> On 11/3/18 5:45 AM, Wolfgang Grandegger wrote: >>>> Hello Dan, >>>> >>>> Am 31.10.2018 um 21:15 schrieb Dan Murphy: >>>>> Wolfgang >>>>> >>>>> Thanks for the review >>>>> >>>>> On 10/27/2018 09:19 AM, Wolfgang Grandegger wrote: >>>>>> Hello Dan, >>>>>> >>>>>> for the RFC, could you please just do the necessary changes to the >>>>>> existing code. We can discuss about better names, etc. later. For >>>>>> the review if the common code I quickly did: >>>>>> >>>>>> mv m_can.c m_can_platform.c >>>>>> mv m_can_core.c m_can.c >>>>>> >>>>>> The file names are similar to what we have for the C_CAN driver. >>>>>> >>>>>> s/classdev/priv/ >>>>>> variable name s/m_can_dev/priv/ >>>>>> >>>>>> Then your patch 1/3 looks as shown below. I'm going to comment on that >>>>>> one. The comments start with "***".... >>>>>> >>>>> >>>>> So you would like me to align the names with the c_can driver? >>>> >>>> That would be the obvious choice. >>>>> <snip> >>>>>> >>>>>> *** I didn't review the rest of the patch for now. >>>>>> >>>>> >>>>> snipped the code to reply to the comment. >>>>> >>>>>> Looking to the generic code, you didn't really change the way >>>>>> the driver is accessing the registers. Also the interrupt handling >>>>>> and rx polling is as it was before. Does that work properly using >>>>>> the SPI interface of the TCAN4x5x? >>>>> >>>>> I don't want to change any of that yet. Maybe my cover letter was not clear >>>>> or did not go through. >>>>> >>>>> But the intention was just to break out the functionality to create a MCAN framework >>>>> that can be used by devices that contain the Bosch MCAN core and provider their own protocal to access >>>>> the registers in the device. >>>>> >>>>> I don't want to do any functional changes at this time on the IP code itself until we have a framework. >>>>> There should be no regression in the io mapped code. >>>>> >>>>> I did comment on the interrupt handling and asked if a threaded work queue would affect CAN timing. >>>>> For the original TCAN driver this was the way it was implemented. >>>> >>>> Do threaded interrupts with RX polling make sense? I think we need a >>>> common interface allowing to select hard-irqs+napi or threaded-irqs. >>>> >>> >>> I have been working on this code for about a month now and I am *not happy* with the amount of change that needs >>> to be done to make the m_can a framework. >>> >>> I can tx/rx frames from another CAN device to the TCAN part but I have not even touched the iomapped code. >>> >>> The challenging part is that the m_can code that is currently available does not have to worry about atomic context because >>> there is no peripheral waiting. Since the TCAN is a peripheral device we need to take into about the hard waits in IRQ context >>> as well as the atomic context. Doing this creates many deltas in the base code that may break iomapped devices. I have had to >>> add the thread_irqs and now I am in the midst of the issue you brought up with napi. I would have to schedule a queue for perp devices >>> and leave the non-threaded iomapped irq. >>> >>> At this point I think it may be wise to leave the m_can code alone as it is working and stable and just work on the TCAN driver as >>> a standalone driver. A framework would be nice but I think it would destablize the m_can driver which is embedded in many SoC's and >>> we cannot possibly test everyone of them. >> >> Unfortunately, I do not have m_can hardware at hand. > > There are exactly 3 platforms in mainline that use the m_can driver. I can help Dan test it on a dra76x. I haven't had a chance to look at the changes in depth, but just testing for regressions on existing platforms shouldn't be too hard once we have it working on one. > Thanks Faiz. Once I have the TCAN fully working I will post the branch to my repo. Dan > Thanks, > Faiz > >> >>> What are your thoughts? >> >> What we need is a common set of functions doing tx, rx, error and state >> handling. This will requires substantial changes to the existing >> io-mapped m_can driver, of course. I still believe it's worth the >> effort, but I agree that it's difficult for you to re-write and test the >> existing m_can driver. >> >> What about implementing such a set of common functions plus the SPI >> specific part for your TCAN device. What do you/others think? >> >> Wolfgang. >> -- ------------------ Dan Murphy
