On Mon, May 16, 2011 at 9:51 AM, Philip Rakity <prakity@xxxxxxxxxxx> wrote: > > On May 15, 2011, at 11:26 PM, zhangfei gao wrote: > >> On Sat, May 14, 2011 at 1:01 PM, Philip Rakity <prakity@xxxxxxxxxxx> wrote: >>> >>> On May 13, 2011, at 10:11 PM, zhangfei gao wrote: >>> >>>> On Fri, May 13, 2011 at 9:47 PM, Chris Ball <cjb@xxxxxxxxxx> wrote: >>>>> Hi, >>>>> >>>>> On Thu, May 12 2011, Philip Rakity wrote: >>>>>> All other platform specific code is in the host/ directory. >>>>>> >>>>>> This moves it to arch/arm >>>>>> >>>>>> If that is the direction the group wants to go in --> then the patch >>>>>> is fine provided the mmc group can review the patches. Otherwise they >>>>>> are handled by the arm maintainer. >>>>> >>>>> Thanks. Wolfram, do you have any ideas on what the best design is for >>>>> these SoC-specific changes to sdhci-pxa? >>>>> >>>>> - Chris. >>>> >>>> The code in arch/arm is >>>> 1. Accessing private register, take pxa910 and mmp2 we want to support >>>> as example, there are several private registers differece, though they >>>> are same ip, with same issues and quirk. >>>> 2. Handle platform difference, for example, mmp2 used in two different >>>> platform, one use wp pin, the other does not. >>> >>> The situation is a little more complicated. >> >> The interface is used for long time among mmp2, pxa910 and mmp3. >> Also could be used for new controller with minor register difference >> but same ip, without adding new specific driver. > > applies to both approaches. The mmp2 specific code can be applied to other marvell > platforms that share the same controller. Just change Kconfig and the Makefile to use > the mmp2 code. The name of the file is not the important thing. It is what it does. > > The pxa168 and pxa910 code are a little less sharable due to io accessors and some > other quirks. > > For other following the discussion we are probably talking about 100 liens of code. > > The philosophical location of where the code belongs for host specific drivers is > to me more important. > > Is it in arch/arm and not directly visible to the mmc list or is it like all other platform drivers > in drivers/mmc/host. The code handle several register difference are located at arch/arm/mach-mmp/mmp2.c is for mmp2 arch/arm/mach-mmp/pxa910.c is for pxa910 serious, arch/arm/mach-mmp/mmp3.c is for mmp3 serious, considering there may still registers changing. The board difference are directly put in board.c For example ttc_dkb do not use wp pin, so get_ro is provided. > > > >> >>> >>> pxa168 and pxa910 share (almost) the same IP The are both based on SD 2.0 >>> controller spec with extensions. The pxa910 controller has fixes to the >>> pxa168 controller. They share the same private registers that allow support >>> for clock gating and timing adjustments. >>> >>> mmp2 is based on SD 3.0 spec. The private register space is different. >>> >>> mmc/host/Kconfig takes no account of these differences. mmp2 and pxa168/910 >>> cannot co-exist. What is currently submitted does not work. One cannot >>> compile mmp2 and pxa910 nor would they work if one could. >>> >>> Mark Brown and I submitted patches to fix this. We added code to the host/ directory >>> that took into account these differences. It provided a common interface layer >>> that then used platform specific code in the host/ directory to handle the different >>> behavior. >>> >>> Arng Bergmann provided advice and reviewed the patches to allow explicit selection of the >>> pxa familty controller and board. Based on this comments we submitted a patch >>> to allow selection if the appropriate SoC. >>> >>> These are two approaches. >>> >>>> >>>> Thanks >>>>> -- >>>>> Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/> >>>>> One Laptop Per Child >>>>> >>> >>> > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
