Re: [PATCH] mtd: rawnand: qcom: update last code word register
From: Miquel Raynal
Date: Wed Feb 24 2021 - 11:41:21 EST
Hello,
mdalam@xxxxxxxxxxxxxx wrote on 2021年2月24日 22:00:05 +0530:
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On 2021年02月24日 12:18, Miquel Raynal wrote:
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> Hello,
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> mdalam@xxxxxxxxxxxxxx wrote on 2021年2月24日 10:09:48 +0530:
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>> On 2021年02月24日 01:13, mdalam@xxxxxxxxxxxxxx wrote:
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>> > On 2021年02月23日 22:04, Miquel Raynal wrote:
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>> >> Hello,
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>> >> >> Md Sadre Alam <mdalam@xxxxxxxxxxxxxx> wrote on 2021年2月23日
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>> >> 01:34:27 +0530:
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>> >> >>> From QPIC version 2.0 onwards new register got added to read last
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>> >> >> a new
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>> >> >>> codeword. This change will add the READ_LOCATION_LAST_CW_n register.
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>> >> >> Add support for this READ_LOCATION_LAST_CW_n register.
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>> >> >>> >>> For first three code word READ_LOCATION_n register will be
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>> >>> use.For last code word READ_LOCATION_LAST_CW_n register will be
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>> >>> use.
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>> >> >> "
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>> >> In the case of QPIC v2, codewords 0, 1 and 2 will be accessed through
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>> >> READ_LOCATION_n, while codeword 3 will be accessed through
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>> >> READ_LOCATION_LAST_CW_n.
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>> >> "
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>> >> >> When I read my own sentence, I feel that there is something wrong.
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>> >> If there are only 4 codewords, I guess a QPIC v2 is able to use
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>> >> READ_LOCATION_3 or READ_LOCATION_LAST_CW_0 interchangeably. Isn't it?
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>> >> >> I guess the point of having these "last_cw_n" registers is to support
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>> >> up to 8 codewords, am I wrong? If this the case, the current patch
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>> >> completely fails doing that I don't get the point of such change.
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>> >
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>> > This register is only use to read last code word.
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>> >
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>> > I have address all the comments from all the previous sub sequent
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>> > patches and pushed
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>> > all patches in only one series.
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>> >
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>> > Please check.
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>> >> The registers READ_LOCATION & READ_LOCATION_LAST are not associated >> with number of code words.
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>> These two registers are used to access the location inside a code >> word.
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> Ok. Can you please explain what is a location then? Or point me to a
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> datasheet that explains it.
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The location is the position inside a code word.
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> Bottom line question: why having READ_LOCATION_0, _1,... an
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> READ_LOCATION_LAST_0, _1, etc?
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READ_LOCATION_0, _1,... are used to extract multiple chunks from a code word.
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e.g If we wanted to extract first 100 bytes from a code word then (0...99) READ_LOCATION_0 will be configured.
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if we wanted to extract next 100 bytes (100...199) then READ_LOCATION_1 will be configured.
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same way for last code word READ_LOCATION_LAST_0, _1, will be used.
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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