mtd: rawnand: use longest matching pattern (2099920e) · Commits · 戴 / test

Sometimes the exec_op parser does not choose the optimal pattern if multiple patterns with optional elements are available. Since the stack automatically splits operations in multiple exec_op calls, a non-optimal pattern gets broken up into multiple calls. E.g. an OOB read using the vf610 driver: nand: executing subop: nand: ->CMD [0x00] nand: ->ADDR [5 cyc: 00 08 ea 94 02] nand: ->CMD [0x30] nand: ->WAITRDY [max 200000 ms] nand: DATA_IN [64 B] nand: executing subop: nand: CMD [0x00] nand: ADDR [5 cyc: 00 08 ea 94 02] nand: CMD [0x30] nand: WAITRDY [max 200000 ms] nand: ->DATA_IN [64 B] However, the vf610 driver has a pattern which can execute the complete command in a single go... This patch makes sure that the longest matching pattern is chosen instead of the first (potentially only partial) match. With this change the vf610 reads the OOB in a single exec_op call: nand: executing subop: nand: ->CMD [0x00] nand: ->ADDR [5 cyc: 00 08 c0 1d 00] nand: ->CMD [0x30] nand: ->WAITRDY [max 200000 ms] nand: ->DATA_IN [64 B] Reported-by:

Sascha Hauer <s.hauer@pengutronix.de> Suggested-by:

Boris Brezillon <boris.brezillon@collabora.com> Tested-by:

Stefan Agner <stefan@agner.ch> Signed-off-by:

Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/nand_base.c

+37 −13

Original line number	Diff line number	Diff line
		@@ -2156,6 +2156,22 @@ static void nand_op_parser_trace(const struct nand_op_parser_ctx *ctx)
		}
		#endif

		static int nand_op_parser_cmp_ctx(const struct nand_op_parser_ctx *a,
		const struct nand_op_parser_ctx *b)
		{
		if (a->subop.ninstrs < b->subop.ninstrs)
		return -1;
		else if (a->subop.ninstrs > b->subop.ninstrs)
		return 1;

		if (a->subop.last_instr_end_off < b->subop.last_instr_end_off)
		return -1;
		else if (a->subop.last_instr_end_off > b->subop.last_instr_end_off)
		return 1;

		return 0;
		}

		/**
		* nand_op_parser_exec_op - exec_op parser
		* @chip: the NAND chip
		@@ -2190,32 +2206,40 @@ int nand_op_parser_exec_op(struct nand_chip *chip,
		unsigned int i;

		while (ctx.subop.instrs < op->instrs + op->ninstrs) {
		int ret;
		const struct nand_op_parser_pattern *pattern;
		struct nand_op_parser_ctx best_ctx;
		int ret, best_pattern = -1;

		for (i = 0; i < parser->npatterns; i++) {
		const struct nand_op_parser_pattern *pattern;
		struct nand_op_parser_ctx test_ctx = ctx;

		pattern = &parser->patterns[i];
		if (!nand_op_parser_match_pat(pattern, &ctx))
		if (!nand_op_parser_match_pat(pattern, &test_ctx))
		continue;

		nand_op_parser_trace(&ctx);

		if (check_only)
		break;

		ret = pattern->exec(chip, &ctx.subop);
		if (ret)
		return ret;
		if (best_pattern >= 0 &&
		nand_op_parser_cmp_ctx(&test_ctx, &best_ctx) <= 0)
		continue;

		break;
		best_pattern = i;
		best_ctx = test_ctx;
		}

		if (i == parser->npatterns) {
		if (best_pattern < 0) {
		pr_debug("->exec_op() parser: pattern not found!\n");
		return -ENOTSUPP;
		}

		ctx = best_ctx;
		nand_op_parser_trace(&ctx);

		if (!check_only) {
		pattern = &parser->patterns[best_pattern];
		ret = pattern->exec(chip, &ctx.subop);
		if (ret)
		return ret;
		}

		/*
		* Update the context structure by pointing to the start of the
		* next subop.

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