* Peter Barada <pet...@logicpd.com> [090806 19:31]: > On Thu, 2009-08-06 at 11:09 -0400, Philip Balister wrote: > > Kevin Hilman wrote: > > > John Sarman <johnsar...@gmail.com> writes: > > > > > >> On Wed, Aug 5, 2009 at 2:35 PM, Kevin > > >> Hilman<khil...@deeprootsystems.com> wrote: > > >>> Steve Sakoman wrote: > > >>>> On Wed, Aug 5, 2009 at 10:58 AM, Kevin > > >>>> Hilman<khil...@deeprootsystems.com> wrote: > > >>>>> Steve Sakoman wrote: > > >>>>>> And up to now in each case I shrug and say "no time to do that now, > > >>>>>> I'll just leave kernel pinmuxing turned off and do it in u-boot" > > >>>>> I agree there are lots of shortcomings in the current mux code and > > >>>>> we've > > >>>>> been hitting them regularily lately. > > >>>>> > > >>>>> That being said, for mux settings that done one-time only at boot, > > >>>>> what > > >>>>> are > > >>>>> the problems you're running into? > > >>>> It's been a few months since I last encountered this, so the exact > > >>>> details are a bit fuzzy. > > >>>> > > >>>> I seem to recall that there were some basic issues with enabling > > >>>> kernel pinmuxing in that some of the setup that was done for all > > >>>> machines was just wrong for my particular machine. IIRC, it was due > > >>>> to assumptions about which pad was used for a particular function (for > > >>>> those functions which can be steered to multiple GPIO pads). > > >>>> > > >>>> So I faced having to undo that change in my board file as well as any > > >>>> issues that may have arisen from glitches on the GPIO pins during the > > >>>> process. And since there were several of these I gave up and turned > > >>>> off kernel pinmuxing. > > >>>> > > >>>> I'd be happy if we cleaned up the "one size fits all" pinmuxing to > > >>>> just that subset that truly does fit all boards, and leave the rest to > > >>>> the board files. I'd also be content to have it all done in the board > > >>>> file for each machine. > > >>> Indeed, any assumptions about common muxing that are not indeed common > > >>> are > > >>> bugs and should be fixed. > > >>> > > >>> The "right" solution is to have everything in the kernel, and split > > >>> across > > >>> SoC "common" init and board specific init. Of course u-boot > > >>> will still have to do some early muxing, but it should be redone in > > >>> the kernel so it's trivial to change bootloaders. > > >>> > > >>> So the real missing piece is someone to step up and rework the mux code. > > >>> The bigger problem is that the vast majority of folks don't care about > > >>> the > > >>> common case and only care about getting thing working for a specific > > >>> platform. > > >>> > > >>> Kevin > > >>> > > >> I like the idea of having the board file configure the mux. First of > > >> all lets address the shortcomings of mux.h. The Pin values are > > >> labeled as so: > > >> <snip from mux.h> > > >> * NOTE: Please use the following naming style for new pin entries. > > >> * For example, W8_1610_MMC2_DAT0, where: > > >> * - W8 = ball > > >> * - 1610 = 1510 or 1610, none if common for both 1510 and > > >> 1610 > > >> * - MMC2_DAT0 = function > > >> > > >> But lets take the 3530 as an example. > > >> The 3530 has three separate packages. CBB, CBC, and CUS. Now lets > > >> look at MMC3_clk (the root of my original problem that started this > > >> thread) > > >> CBB CBC CUS > > >> mmc3_clk AB1 / AF10 R9 / AB2 AC1 > > >> > > >> So to properly add these to mux.h we need to add 5 entries for mmc3_clk > > >> AB1_35XXCBB_MMC3_CLK > > >> AF10_35XXCBB_MMC3_CLK > > >> R9_35XXCBC_MMC3_CLK > > >> AB2_35XXCBC_MMC3_CLK > > >> AC1_35XXCUS_MMC3_CLK > > >> We would then have to update mux.c making sure the position matches > > >> and add the proper settings. > > >> > > >> So this is obviously a maintenance nightmare. > > > > > > So why don't we drop the ball (pun intended.) ;) > > > > > > This is what I proposed to Phillip Ballister for his SPI changes for > > > Beagle. > > > > > > Though I haven't looked at the details for each package, I have a hard > > > time imagining that the reg offsets and functionality for each package > > > is different. In fact, I'm pretty sure they're even the same between > > > 34xx and 35xx. > > > > > > IOW, why not just name it OMAP3_MMC3_CLK and have a single entry. > > > > > > Then each board file that cares simply has to call omap_cfg_reg() on > > > that name and not care about the package. > > > > They first problem I see is the MMC3_CLK is available on multiple balls, > > so the mux files need to list them all. > > > > Unless you are proposing custom mux files for each board? Is this is > > good idea (just had this thought). In other words, instead of trying to > > come up with one set of mux files, make them board specific. > > Here's an idea: > > 1) Replace index with enum search in pin table - this breaks the > requirement that the enum list and table align - a good thing as > misalingment has bitten me multiple times when adding pins to the > current mux table. Also, pinmux setup is done infrequently, so the > search doesn't add much overall execution time.
Yeh something like that sounds good. We should just move the omap1 specific code to live in mach-omap1 and keep it as it is for now. You might also want to take a look at what the sh people have done: $ find arch/sh -name \*mux* > 2) Break up mux table into two parts, the "common" mux list, and a > "custom" mux list - the latter in the board file, and add a function to > add the custom mux list to mux lists searched by omap_cfg_reg(). > > 3) Search the custom mux list first (if specified - allows replacing an > entry in the common table if hardware required differences in > termination, custom pins for GPIO, etc). > > For example, on the OMAP3530, balls H18-H21 can be associated with > either UART3, or GPIOs 163-166. In the common mux list (where multiple > boards use those pins for UART3, the common mux file can have the > entries: > > H18_35XX_UART3_CTS > H19_35XX_UART3_RTS > H20_35XX_UART3_RX > H21_35XX_UART_TX > > that sets up the mux for those pines as a UART. If a board wants to use > those pins instead for GPIO, then in the board file it can have a custom > mux list with: > > H18_35XX_GPIO_163 > H19_35XX_GPIO_164 > H20_35XX_GPIO_165 > H21_35XX_GPIO_166 > > and call into the mux code to add the custom mux list to be searched > first. > > Thoughts? Sounds pretty good to me! Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
