Hi Aaron, On 10/13/2016 03:23 PM, Aaron Williams wrote: > Hi all, > > I'm working on a eMMC/SD driver for our Thunder ARMv8 SoCs by porting the > MIPS driver I wrote earlier but I'm running into some issues and have some > comments. > > First of all, our SoC performs a number of high-level operations in hardware > which are not supported by the U-Boot model. The biggest issue is how we > handle data transfers. We do not support sending CMD12 to stop a transmission > and instead rely on CMD23 for multi-sector transfers. The > mmc_read_blocks/mmc_write_blocks functions don't work with our hardware. For > our Octeon SoC I basically had to replicate everything in mmc.c for our SoC > and replace all of the functionality. I am wondering if this is considered > acceptable because our hardware just does not fit the U-Boot MMC driver model > very well. I also ran into a lot of issues with > sd_send_op_cond/mmc_send_op_cond. Our SoC hardware also automatically handles > things like polling the status. It would be nice if most or all of the > functions inside mmc.c could be overridden by the driver.
If CMD12 didn't support on your SoC, it should be just used CMD23. (or just use only single block read/write.) But as you mentioned, it needs to implement for your SoC..(It should be split to driver for yours.) Because it's not supported on u-boot mainline. (As i know, u-boot-mmc didn't support the pre-defined read/write about normal case.) There is a problem..when error is occurred..because it can't send the stop command.. Well..pre-defined concept can be applied on u-boot, but other things need to discuss about applying on u-boot. I want to know how handles things like polling the status..? If then don't need to send continuously for sd/mmc_op_cond...just return and waiting for completing..? > > Also, our MMC controller shows up as a PCI device but the single PCI device > can handle up to four MMC slots using the same registers. The probe support > does not allow for this. There can be multiple PCI devices as well in our > NUMA configurations, with one PCI device per SoC. This also needs to make the slot concept..but slot concept should not be good thing. And u-boot is running only one thread..so i think it's similar to using 4 IPs.. If you want to discuss about this more..i will check more..how we improve this. :) Anyway..I'm checking my other tasks..After finishing mine..i will reply more things. Best Regards, Jaehoon Chung > > -Aaron _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
