linux-kernel - [PATCH v2] mtd: rawnand: davinci: Reduce polling interval in NAND_OP_WAITRDY

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Message-Id: <20241219-patch-nand-poll-v2-1-cc80a1ee4e0f@bootlin.com>
Date: Thu, 19 Dec 2024 15:58:10 +0100
From: Bastien Curutchet <bastien.curutchet@...tlin.com>
To: Miquel Raynal <miquel.raynal@...tlin.com>, 
 Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>
Cc: linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Herve Codina <herve.codina@...tlin.com>, 
 Bastien Curutchet <bastien.curutchet@...tlin.com>, 
 Christopher Cordahi <christophercordahi@...ometrics.ca>
Subject: [PATCH v2] mtd: rawnand: davinci: Reduce polling interval in
 NAND_OP_WAITRDY_INSTR

For each NAND_OP_WAITRDY_INSTR operation, the NANDFSR register is
polled only once every 100 us to check for the EMA_WAIT pin. This
isn't frequent enough and causes delays in NAND accesses.

Set the polling interval to 0s. It increases the page read speed
reported by flash_speed by ~40% (~30% on page writes).

Signed-off-by: Bastien Curutchet <bastien.curutchet@...tlin.com>
---
Changes in v2:
- Fix SOB.
- Link to v1: https://lore.kernel.org/r/20241219-patch-nand-poll-v1-1-605e5f15f24a@bootlin.com
---
 drivers/mtd/nand/raw/davinci_nand.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/davinci_nand.c b/drivers/mtd/nand/raw/davinci_nand.c
index 1f8354acfb50b2f4d155cdfc03afcf2863539f66..b3fe6f62bb3bd6a51da891c604d38142055ab1d3 100644
--- a/drivers/mtd/nand/raw/davinci_nand.c
+++ b/drivers/mtd/nand/raw/davinci_nand.c
@@ -724,7 +724,7 @@ static int davinci_nand_exec_instr(struct davinci_nand_info *info,
 	case NAND_OP_WAITRDY_INSTR:
 		timeout_us = instr->ctx.waitrdy.timeout_ms * 1000;
 		ret = readl_relaxed_poll_timeout(info->base + NANDFSR_OFFSET,
-						 status, status & BIT(0), 100,
+						 status, status & BIT(0), 0,
 						 timeout_us);
 		if (ret)
 			return ret;

---
base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37
change-id: 20241219-patch-nand-poll-b215766ea0a2

Best regards,
-- 
Bastien Curutchet <bastien.curutchet@...tlin.com>