linux-kernel - [PATCH] spi: spi-qpic-snand: remove superfluous qcom_spi_set_read

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Message-Id: <20251129-qpic-snand-superfluous-readloc-v1-1-b84ca17095d9@gmail.com>
Date: Sat, 29 Nov 2025 11:29:27 +0100
From: Gabor Juhos <j4g8y7@...il.com>
To: Mark Brown <broonie@...nel.org>
Cc: linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Md Sadre Alam <quic_mdalam@...cinc.com>, 
 Varadarajan Narayanan <quic_varada@...cinc.com>, 
 Sricharan Ramabadhran <quic_srichara@...cinc.com>, 
 linux-mtd@...ts.infradead.org, linux-arm-msm@...r.kernel.org, 
 Gabor Juhos <j4g8y7@...il.com>
Subject: [PATCH] spi: spi-qpic-snand: remove superfluous
 qcom_spi_set_read_loc() calls

Before configuring the registers related to page read, both the
qcom_spi_read_page_ecc() and the qcom_spi_read_page_oob() functions
are calling qcom_spi_set_read_loc() to set the read location for the
first codeword.

However the qcom_spi_set_read_loc() function puts the passed value
into the register write cache only, from where those gets written
to the corresponding register later via DMA.

Yet, the qcom_spi_set_read_loc() is also gets called within the
internal loops, and during the first iteration the read location
register values written by the initial call gets overwritten in
the register cache.

This means that the values written by the first calls are never
getting used in practice, so remove the calls as those are
superfluous.

Signed-off-by: Gabor Juhos <j4g8y7@...il.com>
---
 drivers/spi/spi-qpic-snand.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/spi/spi-qpic-snand.c b/drivers/spi/spi-qpic-snand.c
index 7681a91d67d563fd21fcbd69d223b6e846e97787..0334ba738bef2811e3458d20ce69bd3a213cb20b 100644
--- a/drivers/spi/spi-qpic-snand.c
+++ b/drivers/spi/spi-qpic-snand.c
@@ -850,8 +850,6 @@ static int qcom_spi_read_page_ecc(struct qcom_nand_controller *snandc,
 	snandc->regs->ecc_bch_cfg = cpu_to_le32(ecc_bch_cfg);
 	snandc->regs->exec = cpu_to_le32(1);
 
-	qcom_spi_set_read_loc(snandc, 0, 0, 0, ecc_cfg->cw_data, 1);
-
 	qcom_clear_bam_transaction(snandc);
 
 	qcom_write_reg_dma(snandc, &snandc->regs->addr0, NAND_ADDR0, 2, 0);
@@ -941,8 +939,6 @@ static int qcom_spi_read_page_oob(struct qcom_nand_controller *snandc,
 	snandc->regs->ecc_bch_cfg = cpu_to_le32(ecc_bch_cfg);
 	snandc->regs->exec = cpu_to_le32(1);
 
-	qcom_spi_set_read_loc(snandc, 0, 0, 0, ecc_cfg->cw_data, 1);
-
 	qcom_write_reg_dma(snandc, &snandc->regs->addr0, NAND_ADDR0, 2, 0);
 	qcom_write_reg_dma(snandc, &snandc->regs->cfg0, NAND_DEV0_CFG0, 3, 0);
 	qcom_write_reg_dma(snandc, &snandc->regs->erased_cw_detect_cfg_clr,

---
base-commit: cb5c2eb459f4c98d584eaf3d3ea7c3612385d081
change-id: 20251128-qpic-snand-superfluous-readloc-c7c245a20a46

Best regards,
-- 
Gabor Juhos <j4g8y7@...il.com>