Messages in this thread | | | Date | Wed, 24 Feb 2021 17:36:44 +0100 | From | Miquel Raynal <> | Subject | Re: [PATCH] mtd: rawnand: qcom: update last code word register |
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Hello,
mdalam@codeaurora.org wrote on Wed, 24 Feb 2021 22:00:05 +0530:
> On 2021-02-24 12:18, Miquel Raynal wrote: > > Hello, > > > > mdalam@codeaurora.org wrote on Wed, 24 Feb 2021 10:09:48 +0530: > > > >> On 2021-02-24 01:13, mdalam@codeaurora.org wrote: > >> > On 2021-02-23 22:04, Miquel Raynal wrote: > >> >> Hello, > >> >> >> Md Sadre Alam <mdalam@codeaurora.org> wrote on Tue, 23 Feb 2021 > >> >> 01:34:27 +0530: > >> >> >>> From QPIC version 2.0 onwards new register got added to read last > >> >> >> a new > >> >> >>> codeword. This change will add the READ_LOCATION_LAST_CW_n register. > >> >> >> Add support for this READ_LOCATION_LAST_CW_n register. > >> >> >>> >>> For first three code word READ_LOCATION_n register will be > >> >>> use.For last code word READ_LOCATION_LAST_CW_n register will be > >> >>> use. > >> >> >> " > >> >> In the case of QPIC v2, codewords 0, 1 and 2 will be accessed through > >> >> READ_LOCATION_n, while codeword 3 will be accessed through > >> >> READ_LOCATION_LAST_CW_n. > >> >> " > >> >> >> When I read my own sentence, I feel that there is something wrong. > >> >> If there are only 4 codewords, I guess a QPIC v2 is able to use > >> >> READ_LOCATION_3 or READ_LOCATION_LAST_CW_0 interchangeably. Isn't it? > >> >> >> I guess the point of having these "last_cw_n" registers is to support > >> >> up to 8 codewords, am I wrong? If this the case, the current patch > >> >> completely fails doing that I don't get the point of such change. > >> > > >> > This register is only use to read last code word. > >> > > >> > I have address all the comments from all the previous sub sequent > >> > patches and pushed > >> > all patches in only one series. > >> > > >> > Please check. > >> >> The registers READ_LOCATION & READ_LOCATION_LAST are not associated >> with number of code words. > >> These two registers are used to access the location inside a code >> word. > > > > Ok. Can you please explain what is a location then? Or point me to a > > datasheet that explains it. > > The location is the position inside a code word. > > > > > Bottom line question: why having READ_LOCATION_0, _1,... an > > READ_LOCATION_LAST_0, _1, etc? > > READ_LOCATION_0, _1,... are used to extract multiple chunks from a code word. > > e.g If we wanted to extract first 100 bytes from a code word then (0...99) READ_LOCATION_0 will be configured. > if we wanted to extract next 100 bytes (100...199) then READ_LOCATION_1 will be configured. > > same way for last code word READ_LOCATION_LAST_0, _1, will be used. >
Nice explanation, and thanks for the below figures. So I guess there is some kind of "small SRAM" that is directly addressable perhaps?
I think I'm fine with your series now. Just a small nit: next time you send a series, please update the version number "[PATCH v6]" (automatically added with the -v6 parameter in git-format-patch). But no need to resend just for that.
Thanks, Miquèl
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