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Date: Fri, 13 Oct 2017 17:34:30 +0900 From: Masahiro Yamada <yamada.masahiro@...ionext.com> To: Marc Gonzalez <marc_gonzalez@...madesigns.com> Cc: Boris Brezillon <boris.brezillon@...e-electrons.com>, Mason <slash.tmp@...e.fr>, Richard Weinberger <richard@....at>, LKML <linux-kernel@...r.kernel.org>, Marek Vasut <marek.vasut@...il.com>, linux-mtd <linux-mtd@...ts.infradead.org>, Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>, Brian Norris <computersforpeace@...il.com>, David Woodhouse <dwmw2@...radead.org> Subject: Re: [PATCH v2 0/2] mtd: nand: wait for tWHR, and fix the setup_data_interface of Denali Hi Marc, 2017-10-04 20:05 GMT+09:00 Marc Gonzalez <marc_gonzalez@...madesigns.com>: > On 29/09/2017 16:33, Masahiro Yamada wrote: > >> (+CC Marc Gonzalez) >> >> 2017-09-29 21:26 GMT+09:00 Boris Brezillon <boris.brezillon@...e-electrons.com>: >>> On Fri, 29 Sep 2017 19:38:38 +0900 >>> Masahiro Yamada <yamada.masahiro@...ionext.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. >> >> Perhaps, Marc Gonzalez is the person. >> >> >> tango_nand.c is the only driver that sets NAND_WAIT_TCCS. >> >> Now, there is completely no delay when reading out the ID. >> >> >> One safe change might be apply this patch, >> then set NAND_WAIT_TWHR to tango_nand.c >> >> >> I am guessing NAND_WAIT_TCCS was added for it. >> Theoretically, I do not see logical difference between tCCS and tWHR. >> >> I am CCing Marc Gonzalez, the author of tango_nand.c > > Hello Masahiro, > > I remember having issues reading the ONFI ID when I was writing > the driver, a year ago. Sometimes, the first few bytes appeared > to be missing. This looked like a timing issue. > > Adding the dev_ready call-back solved the problem. Do you think > that was by accident? It is odd to use dev_ready() hook to insert delay for the READ ID command. READ ID command never toggles the device's Ready/Busy# pin. > When I have more time, I will test the 4.14 > branch, to see if there are any issues with the current driver. Yeah, I highly recommend you to test your driver on the latest kernel. I suspect it is broken because READ ID command in the generic hook has absolutely zero delay. As I proposed already, the correct fix it to wait for tWHR. -- Best Regards Masahiro Yamada
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