Hi Chuanxiao, I have a question from the review of your SW CMDQ driver code.
>From the eMMC5.1 spec, the "ready for execution" for each task should be >cleared by the device only when the last data block has been fully transferred >over the eMMC bus. However, from the code, I can recognize the following suspected case: 1. Host sends CMD44/45 commands for TID#0 2. Host sends CMD13 (QSR) -> returned TID#0 ready for execution 3. Host sends CMD46 for TID#0 4. During the data transfer, host may send CMD13 (QSR) -> returned TID#0 ready for execution (which is true since data is still in transfer) 5. Host sends CMD46 for TID#0 (same as sent in bullet#3) - which is a problem. Please advise if my assumption above is correct. Thanks, Alex > -----Original Message----- > From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc- > ow...@vger.kernel.org] On Behalf Of Chuanxiao Dong > Sent: Friday, December 19, 2014 10:05 AM > To: linux-mmc@vger.kernel.org > Subject: [RFC PATCH 0/5]mmc: Soft Command queue implementation for > eMMC5.1 device > > Hello, > > Seems community already have some implementation for the eMMC5.1 device > command queue feature, but that require the eMMC host controller to support > CMDQ. In my platform, I don't have this kind of eMMC host controller but I > have a Samsung eMMC5.1 device which can support the Command queue. > > With this limitation, I have to let eMMC host controller to manually send the > CMD44/45/13/46/47. So in this way, more commands are needed for an I/O > request, more interrupts/schedule are needed in driver. > > Even this way have some more software overhead, but it can still use the > eMMC5.1 device Command queue feature. After test with the iozone > command: > "iozone -zec -t 4 -i0 -i2 -F iozonefile1 iozonefile2 iozonefile3 iozonefile4 > -+n -I -r > 4k -s 500m -O -R -+r -+D" to test random performance, I saw a performance > improvment for random read on my eMMC5.1 device: > > Random read > SW CMDQ: 5544.6 > Normal Read: 3993.05 > > So I want to send this serial patches as RFC patch for reviewing > > > Chuanxiao Dong (5): > mmc: replace sbc to precmd and add postcmd > mmc: host: add runtime PM for host class dev > mmc: queue: change mqrq_cur and mqrq_pre to mq qdepth > mmc: core: add support for CMDQ feature in MMC Core stack > mmc: sdhci: add SW CMDQ support for CHT SDHCI host > > drivers/mmc/card/block.c | 538 > ++++++++++++++++++++++++++++++++++++++--- > drivers/mmc/card/queue.c | 213 ++++++++-------- > drivers/mmc/card/queue.h | 14 +- > drivers/mmc/core/core.c | 78 +++++- > drivers/mmc/core/host.c | 14 ++ > drivers/mmc/core/mmc.c | 43 +++- > drivers/mmc/host/dw_mmc.c | 8 +- > drivers/mmc/host/mmci.c | 14 +- > drivers/mmc/host/omap_hsmmc.c | 18 +- > drivers/mmc/host/sdhci-acpi.c | 1 - > drivers/mmc/host/sdhci-pci.c | 1 - > drivers/mmc/host/sdhci.c | 137 +++++++++-- > include/linux/mmc/card.h | 3 + > include/linux/mmc/core.h | 5 +- > include/linux/mmc/host.h | 5 + > include/linux/mmc/mmc.h | 21 ++ > include/linux/mmc/pm.h | 1 + > include/linux/mmc/sdhci.h | 1 + > 18 files changed, 909 insertions(+), 206 deletions(-) > > -- > 1.7.10.4 > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the > body > of a message to majord...@vger.kernel.org More majordomo info at > http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
