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Date: Fri, 29 Sep 2017 23:33:28 +0900 From: Masahiro Yamada <yamada.masahiro@...ionext.com> To: Boris Brezillon <boris.brezillon@...e-electrons.com> Cc: linux-mtd@...ts.infradead.org, Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Marek Vasut <marek.vasut@...il.com>, Brian Norris <computersforpeace@...il.com>, Richard Weinberger <richard@....at>, David Woodhouse <dwmw2@...radead.org>, Marc Gonzalez <marc_gonzalez@...madesigns.com> Subject: Re: [PATCH v2 0/2] mtd: nand: wait for tWHR, and fix the setup_data_interface of Denali (+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 commit 6ea40a3ba93e1b14ffb349e276f9dfefc4334b99 Author: Boris Brezillon <boris.brezillon@...e-electrons.com> Date: Sat Oct 1 10:24:03 2016 +0200 mtd: nand: Wait tCCS after a column change Drivers implementing ->cmd_ctrl() and relying on the default ->cmdfunc() implementation usually don't wait tCCS when a column change (RNDIN or RNDOUT) is requested. Add an option flag to ask the core to do so (note that we keep this as an opt-in to avoid breaking existing implementations), and make use of the ->data_interface information is available (otherwise, wait 500ns). Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com> Tested-by: Marc Gonzalez <marc_gonzalez@...madesigns.com> -- Best Regards Masahiro Yamada
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