Messages in this thread | | | From | Masahiro Yamada <> | Date | Fri, 29 Sep 2017 23:06:42 +0900 | Subject | Re: [PATCH v2 0/2] mtd: nand: wait for tWHR, and fix the setup_data_interface of Denali |
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2017-09-29 21:26 GMT+09:00 Boris Brezillon <boris.brezillon@free-electrons.com>: > On Fri, 29 Sep 2017 19:38:38 +0900 > Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > >> 1/2 : add NAND_WAIT_TWHR and nand_whr_delay(). >> You can set this new flag if you want nand_command(_lp) >> to insert tWHR delay where needed. >> >> 2/2 : Fix Denali setup_data_interface. >> Boris' suggestion in v1 was a good reminder that >> made me realize tCCS was missing in the driver. Fix it now. >> >> >> Changes in v2: >> - Add nand_whr_delay() helper >> Wait for tWHR only for drivers that explicitly set NAND_WAIT_TWHR flag >> - newly added >> >> Masahiro Yamada (2): >> mtd: nand: wait for tWHR after NAND_CMD_STATUS / NAND_CMD_READID > > Hm, I thought you were introducing this to then use it in the denali > driver. Sorry, but I don't want to apply something that nobody needs. > If someone ever complains about a missing delay I'll point him to your > patch, but until then I'll keep the core unchanged.
At first, I thought this was necessary for me, but I realized it was my misunderstanding.
Please let me explain one more.
See commit 3158fa0e739615769cc047d2428f30f4c3b6640e.
Prior to that commit, READID waited for #R/B transition, it was wrong, so I fixed it.
However, it dropped the delay completely. If somebody was implicitly relying on the delay of chip->dev_ready, the first byte might be read out before the valid data is available.
This was motivation of v1, where inserted ndelay(200) unconditionally.
>> mtd: nand: denali: fix setup_data_interface to meet tCCS delay > > This one is valid. I'll queue it to nand/next soon.
If you drop 1/2, please let me do v3.
V2 mentions NAND_WAIT_TWHR, this is strange.
-- Best Regards Masahiro Yamada
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