From acb47aa9b1e2f47121cf2233fcaf998151ab5410 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 16 May 2025 15:32:22 +0200 Subject: [PATCH] spi: sh-msiof: Double maximum DMA transfer size using two groups The maximum DMA transfer size is limited by the maximum values that can be written to the word count fields (WDLENx) in the Transmit and Control Data Registers (SITDR2/SIRDR2). As all MSIOF variants support transferring data of multiple (two or four) groups, the maximum size can be doubled by using two groups instead of one, thus reducing setup overhead for very large SPI transfers. Signed-off-by: Geert Uytterhoeven Link: https://patch.msgid.link/bad522c76b8d225c195433977b22f95015cf2612.1747401908.git.geert+renesas@glider.be Signed-off-by: Mark Brown --- drivers/spi/spi-sh-msiof.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c index 2b8c143b2121..4d9a44118e1c 100644 --- a/drivers/spi/spi-sh-msiof.c +++ b/drivers/spi/spi-sh-msiof.c @@ -767,10 +767,12 @@ static void sh_msiof_dma_complete(void *arg) } static int sh_msiof_dma_once(struct sh_msiof_spi_priv *p, const void *tx, - void *rx, unsigned int len) + void *rx, unsigned int len, + unsigned int max_wdlen) { u32 ier_bits = 0; struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL; + unsigned int words1, words2; dma_cookie_t cookie; int ret; @@ -817,7 +819,9 @@ static int sh_msiof_dma_once(struct sh_msiof_spi_priv *p, const void *tx, FIELD_PREP(SIFCTR_RFWM, SIFCTR_RFWM_1)); /* setup msiof transfer mode registers (32-bit words) */ - sh_msiof_spi_set_mode_regs(p, tx, rx, 32, len / 4, 0); + words1 = min(len / 4, max_wdlen); + words2 = len / 4 - words1; + sh_msiof_spi_set_mode_regs(p, tx, rx, 32, words1, words2); sh_msiof_write(p, SIIER, ier_bits); @@ -969,7 +973,7 @@ static int sh_msiof_transfer_one(struct spi_controller *ctlr, * DMA supports 32-bit words only, hence pack 8-bit and 16-bit * words, with byte resp. word swapping. */ - unsigned int l = min(round_down(len, 4), max_wdlen * 4); + unsigned int l = min(round_down(len, 4), 2 * max_wdlen * 4); if (bits <= 8) { copy32 = copy_bswap32; @@ -982,7 +986,7 @@ static int sh_msiof_transfer_one(struct spi_controller *ctlr, if (tx_buf) copy32(p->tx_dma_page, tx_buf, l / 4); - ret = sh_msiof_dma_once(p, tx_buf, rx_buf, l); + ret = sh_msiof_dma_once(p, tx_buf, rx_buf, l, max_wdlen); if (ret == -EAGAIN) { dev_warn_once(&p->pdev->dev, "DMA not available, falling back to PIO\n"); -- 2.50.1