On 26 May 2016 at 03:55, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> wrote: > > Hello all, > > This patch is going to support enhanced strobe function > for emmc version 5.1+ introduced by JEDEC recently. > > Enchanced strobe is a optional function, so we add a new cap* for drivers to > decide whether to use it. > > When introduing hs400 mode, JEDEC asks controllers to use data strobe line > to latch the data from emmc devives. But for cmd-reponse, not mentioned yet. > Since emmc version 5.1 published, JEDEC adds enhanced strobe function to deal > with cmd-response the same way as data-read. This feature is optional. > > From the spec(section 6.6.2.3), the standard scenario to select HS400 enhanced > strobe mode illustrated like this: > (1) set HS_TIMIMG (Highspeed) > (2) Host change freq to <= 52Mhz > (3) set the bus width to Enhanced strobe and DDR8Bit(CMD6), EXT_CSD[183] = 0x86 > instead of 0x80 > (4) set HS_TIMING to 0x3 (HS400) > (5) Host change freq to <= 200Mhz > (6) Host select HS400 enhanced strobe complete > > I can't find a upstreamed controller claimed to support it, as well as the > mmc stack. But my "arasan,sdhci-5.1" actually supports this function. So I decide > to work for this part. > > By looking into the SDHCI spec, I find there isn't any registers to enable the > enhanced strobe function. But from my "arasan,sdhci-5.1" databook, it describes a > register called VENDOR_REGISTER(0x78) to trigger this mode. So I guess other sdhci > variant drivers may also need s vendor specific register to deal with it. > > If we are sure that our controller supports enhanced strobe mode, just add > mmc-hs400-enhanced-strobe in DT. Once emmc devices claims to support this mode, > we enable it automatically. Of course, other sdhci*/non-sdhci drivers should > implement/overwrite the hs400_enhanced_strobe by themselves. I believe all of the > platforms which need to support this mode should do some basic preparation for their > controllers. Currently I just limit the callback within ths scope of arasan,sdhci-5.1, > but I prone to believe arasan will use VENDOR_REGISTER to tirgger this mode from now on > because I do believe vendor will consider the registers' compatibility. > > With this patchset applied, we can successfully run in HS400 enhanced strobe mode on > RK3399 platform with Samsung eMMC KLMBG2JENB-B041(v5.1, 16GB). > > mmc1: new HS400 Enhanced strobe MMC card at address 0001 > mmcblk0: mmc1:0001 AJNB4R 14.6 GiB > mmcblk0boot0: mmc1:0001 AJNB4R partition 1 4.00 MiB > mmcblk0boot1: mmc1:0001 AJNB4R partition 2 4.00 MiB > mmcblk0rpmb: mmc1:0001 AJNB4R partition 3 4.00 MiB > > Also I check this patchset with removing some caps to make sure > all the init sequences for hs400/hs200/DDR52/HighSpeed are correct. > > > Changes in v6: > - add Doug's test-tag and Jaehoon's review-test-tag > - add Doug's review-test-tag and Jaehoon's test-tag > - a minor string assignment > > Changes in v5: > - avoid to call hs400_enhanced+_strobe in mmc_set_initial_state > if no setting MMC_CAP2_HS400_ES. > - add Adrian's ack for patch[5/5] > > Changes in v4: > - check avail_type with EXT_CSD_CARD_TYPE_HS400 instead of > card_type > - check if host support 8-bit when selecting hs400es > - some minor fix suggested by Douglas and add his review tag > > Changes in v3: > - remove helper function and shorten cap2 to MMC_CAP2_HS400_ES > - rename callback to hs400_enhanced_strobe and make it return void > - add enhanced_strobe in mmc_ios and pass it to hs400_enhanced_strobe > - disable host's enhanced strobe in mmc_set_initial_state > - remove bus checking after switching hs400es > - add new function for hs400es timing selection > - fix wrong judgement of mmc_card_hs400es > > Changes in v2: > - switch to HS400ES from Highspeed mode directly > > Shawn Lin (5): > Documentation: mmc: add mmc-hs400-enhanced-strobe > mmc: core: add mmc-hs400-enhanced-strobe support > mmc: core: implement enhanced strobe support > mmc: debugfs: add HS400 enhanced strobe description > mmc: sdhci-of-arasan: implement enhanced strobe callback > > Documentation/devicetree/bindings/mmc/mmc.txt | 1 + > drivers/mmc/core/bus.c | 3 +- > drivers/mmc/core/core.c | 9 +++ > drivers/mmc/core/debugfs.c | 3 +- > drivers/mmc/core/host.c | 2 + > drivers/mmc/core/mmc.c | 84 ++++++++++++++++++++++++++- > drivers/mmc/host/sdhci-of-arasan.c | 20 +++++++ > include/linux/mmc/card.h | 1 + > include/linux/mmc/host.h | 12 ++++ > include/linux/mmc/mmc.h | 3 + > 10 files changed, 134 insertions(+), 4 deletions(-) > Thanks! A very nice series and with lot's of folkz helping out reviewing and testing, great! Applied for next! Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
