From bb415dff3ab73b0e97f031dbc7ca708f76739643 Mon Sep 17 00:00:00 2001 From: Xiaolei Li Date: Tue, 24 Apr 2018 10:11:07 +0800 Subject: dt-bindings: mtd: mtk-nand: Update properties description Update ecc step size, ecc strength, and parity bits supported on each MTK NAND controller. Signed-off-by: Xiaolei Li Signed-off-by: Boris Brezillon --- Documentation/devicetree/bindings/mtd/mtk-nand.txt | 24 +++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) (limited to 'Documentation/devicetree/bindings/mtd/mtk-nand.txt') diff --git a/Documentation/devicetree/bindings/mtd/mtk-nand.txt b/Documentation/devicetree/bindings/mtd/mtk-nand.txt index 1c88526dedfc..f20ab4abd214 100644 --- a/Documentation/devicetree/bindings/mtd/mtk-nand.txt +++ b/Documentation/devicetree/bindings/mtd/mtk-nand.txt @@ -50,14 +50,19 @@ Optional: - nand-on-flash-bbt: Store BBT on NAND Flash. - nand-ecc-mode: the NAND ecc mode (check driver for supported modes) - nand-ecc-step-size: Number of data bytes covered by a single ECC step. - valid values: 512 and 1024. + valid values: + 512 and 1024 on mt2701 and mt2712. + 512 only on mt7622. 1024 is recommended for large page NANDs. - nand-ecc-strength: Number of bits to correct per ECC step. - The valid values that the controller supports are: 4, 6, - 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, 40, 44, - 48, 52, 56, 60. + The valid values that each controller supports: + mt2701: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, + 32, 36, 40, 44, 48, 52, 56, 60. + mt2712: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, + 32, 36, 40, 44, 48, 52, 56, 60, 68, 72, 80. + mt7622: 4, 6, 8, 10, 12, 14, 16. The strength should be calculated as follows: - E = (S - F) * 8 / 14 + E = (S - F) * 8 / B S = O / (P / Q) E : nand-ecc-strength. S : spare size per sector. @@ -66,6 +71,15 @@ Optional: O : oob size. P : page size. Q : nand-ecc-step-size. + B : number of parity bits needed to correct + 1 bitflip. + According to MTK NAND controller design, + this number depends on max ecc step size + that MTK NAND controller supports. + If max ecc step size supported is 1024, + then it should be always 14. And if max + ecc step size is 512, then it should be + always 13. If the result does not match any one of the listed choices above, please select the smaller valid value from the list. -- cgit v1.2.3