6.6-stable review patch. If anyone has any objections, please let me know.
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From: Marek Vasut marek.vasut+renesas@mailbox.org
[ Upstream commit 62abfd7bedc2b3d86d4209a4146f9d2b5ae21fab ]
R-Car V4H Reference Manual R19UH0186EJ0130 Rev.1.30 Apr. 21, 2025 page 583 Figure 9.3.1(a) Software Reset flow (A) as well as flow (B) / (C) indicate after reset has been asserted by writing a matching reset bit into register SRCR, it is mandatory to wait 1ms.
This 1ms delay is documented on R-Car V4H and V4M, it is currently unclear whether S4 is affected as well. This patch does apply the extra delay on R-Car S4 as well.
Fix the reset driver to respect the additional delay when toggling resets. Drivers which use separate reset_control_(de)assert() must assure matching delay in their driver code.
Fixes: 0ab55cf18341 ("clk: renesas: cpg-mssr: Add support for R-Car V4H") Signed-off-by: Marek Vasut marek.vasut+renesas@mailbox.org Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be Link: https://patch.msgid.link/20250918030552.331389-1-marek.vasut+renesas@mailbox... Signed-off-by: Geert Uytterhoeven geert+renesas@glider.be Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clk/renesas/renesas-cpg-mssr.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/clk/renesas/renesas-cpg-mssr.c b/drivers/clk/renesas/renesas-cpg-mssr.c index cb80d1bf6c7c6..55ac571c73884 100644 --- a/drivers/clk/renesas/renesas-cpg-mssr.c +++ b/drivers/clk/renesas/renesas-cpg-mssr.c @@ -612,8 +612,15 @@ static int cpg_mssr_reset(struct reset_controller_dev *rcdev, /* Reset module */ writel(bitmask, priv->base + priv->reset_regs[reg]);
- /* Wait for at least one cycle of the RCLK clock (@ ca. 32 kHz) */ - udelay(35); + /* + * On R-Car Gen4, delay after SRCR has been written is 1ms. + * On older SoCs, delay after SRCR has been written is 35us + * (one cycle of the RCLK clock @ ca. 32 kHz). + */ + if (priv->reg_layout == CLK_REG_LAYOUT_RCAR_GEN4) + usleep_range(1000, 2000); + else + usleep_range(35, 1000);
/* Release module from reset state */ writel(bitmask, priv->base + priv->reset_clear_regs[reg]);