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    SubjectRE: [PATCH v5 2/2] mmc: core: Support packed command for eMMC4.5 device
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    Maya Erez <merez@codeaurora.org> wrote:
    > > Maya Erez <merez@codeaurora.org> wrote:
    > >> > Hi. Merez.
    > >> >
    > >> > Thanks a lot about your performance measurement.
    > >> >
    > >> > I think that your measurement is enough and correct and the firmware
    > >> > of mmc vender should be optimized or change properly rather than
    > >> > modifying the current patch.
    > >> >
    > >> > And currently we can use only write packed cmd by my suggestion.
    > >> >
    > >> > I would like to add my reviewd-by tag in updated patches also.
    > >> >
    > >> > Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
    > >> >
    > >> > Thanks.
    > >>
    > >> I tend to disagree. Adding a massive amount of code that would be
    > >> disabled
    > >> can be risky. In case this code will not be in use it will not be
    > >> properly
    > >> tested and its reliability will be uncertain.
    > >>
    > > If you found something to be correct, please let me know that.
    > > It would be rightly appreciated.
    > >
    > > Best regards,
    > > Seungwon Jeon.
    > Hi Jeon,
    >
    > The write packing code looks good to me.
    > However, the separation of read and write packing to different patches is
    > very important to us.
    > As I specified before, we decided to enable only the write packing. We
    > plan to thoroughly test the write packing (edge cases and error handling)
    > and will not test the read packing. Therefore we would like to have the
    > ability to get only the write packing code.
    As Namjae Jeon mentioned, how about this?
    I think only MMC_CAP2_PACKED_WR can be set for enabling the write packing easily.
    In my case, tested eMMC device is not optimized for packed read.
    So I couldn't confirm that this patch is effective in packed read.
    I think packed read as well as packed write of this patch conformed with the eMMC4.5 spec though.
    I wonder that your eMMC device has the good ability in both operations.
    It is difficult to decide the performance with excluding the device.
    Soon I will test it with the improved sample for packed read.

    > In my previous comment I talked about the risk of mainlining a “dead”
    > code. Every feature that is integrated is considered to be fully tested
    > and in the future it might be enabled, assuming that is was already
    > tested.
    Right! It is desirable and I hope that.
    Do you think this patch have the potential problem?
    As I also ask you, if you have tested and find something is incorrect, we can discuss that.
    It was submitted for that purpose.

    > Can you please specify how you tested the read and write packing? Did you
    > perform edge cases and error handling tests? Do you have test code that
    > can be shared?
    Basically, It has been tested with several I/O benchmark tool.
    Some misvalued I/O timing and wrong argument for packed command
    was used for triggering the error case.

    Best regards,
    Seungwon Jeon.
    >
    > Thanks,
    > Maya Erez
    > Consultant for Qualcomm Innovation Center, Inc.
    > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
    >
    >
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