Pierre Savary wrote: > Then my MMC 4GB works with my Linux kernel but if I can't > load my kernel > (located on the first part of this MMC) ... it's not really > interesting :(
> So, somebody does already use MMC v4 with U-boot??? Assuming a AT91SAM926x MCI controller: Probably. Given an MMC v2.x compliant U-Boot driver, it would be relatively easy to add support for an MMC v4.x chip. If there is an MMC v4.x compliant Linux driver, it could be ported to U-Boot (Many, if not most, U-Boot drivers are ports from the corresponding Linux driver.) Alternatively, if both an MMC v2.x compliant U-Boot driver and MMC v4.x compliant Linux driver exist, the port would be trivial; just copy the MMC v4.x Linux code into the corresponding places in the MMC v2.2 U-Boot driver until it supports your MMC v4.x chip. Such an MMC v4.x U-Boot AT91SAM926x MCI driver should be able to support any v4.x MMC chip, at least via a one bit MMC bus. (I remain unconvinced that the AT91SAM926x MCI controller can support a 4 bit MMC bus; only a working MCI driver using a 4 bit MMC bus verified by a logic analyzer or similar compliance/debugging device would be convincing enough.) If the Linux AT91SAM926x MCI driver supports a 4 bit MMC bus, then the U-Boot AT91SAM926x MCI driver can borrow the Linux driver's code and support a 4 bit bus also. Sincerely, Ken Fuchs > -----Message d'origine----- > De : [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] De la > part de Pierre > Ossman > Envoyé : samedi 12 avril 2008 11:28 > À : [EMAIL PROTECTED] > Cc : [EMAIL PROTECTED]; u-boot-users@lists.sourceforge.net > Objet : Re: [U-Boot-Users] drivers MMCplus for at91sam9x > > On Fri, 11 Apr 2008 13:54:13 -0500 > [EMAIL PROTECTED] wrote: > > > > > The manual for the AT91SAM926x processors clearly states that the > > MCI controller supports MMC 2.2. I asked Atmel whether > this controller > > could support 4 bits to an MMC 4.x chip and they said _no_. > The answer > > is supposedly from their engineering group in France. > > > > What they answered was if Atmel would support such a solution, not if > the hardware would. > > > > > How does one program the MCI controller to send 4 bit > (parallel) data > > an MMC 4.x chip, with or without telling it that it is communicating > > to a 4-bit SD chip? The only way to get 4 bits of data out > of the MCI > > is to tell it that it is connected to a SD (1.0) chip. If > you program > > the MCI to communicate with an MMC chip, it will send data > out only on > > the low order bit. > > You tell it to use all four bits. That's it. The setting isn't MMC/SD, > it's 1-bit/4-bit. > > > Both ends of the communication link must considered. It may not be > > sufficient that the MMC chip is MMC 4.x; The fact that the MCI > > controller is only MMC 2.2 or SD 1.0 compliant, may or may > not impact > > this special handling. > > It does not in the slightest. Remember that these controllers are > extremely dumb. The low level behaviour of the protocol hasn't changed > since the very first specs, so only software needs to be changed to > support even the newest features. > > Rgds > -- > -- Pierre Ossman > > Linux kernel, MMC maintainer http://www.kernel.org > PulseAudio, core developer http://pulseaudio.org > rdesktop, core developer http://www.rdesktop.org > > -------------------------------------------------------------- > ----------- > This SF.net email is sponsored by the 2008 JavaOne(SM) Conference > Don't miss this year's exciting event. There's still time to > save $100. > Use priority code J8TL2D2. > http://ad.doubleclick.net/clk;198757673;13503038;p?http://java .sun.com/javao ne _______________________________________________ U-Boot-Users mailing list U-Boot-Users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/u-boot-users ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ U-Boot-Users mailing list U-Boot-Users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/u-boot-users
