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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606f26392esm59281440f8f.3.2026.06.17.21.50.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2026 21:50:33 -0700 (PDT) From: David Carlier To: Michael Turquette , Stephen Boyd Cc: Brian Masney , Xukai Wang , Conor Dooley , Troy Mitchell , linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, David Carlier Subject: [PATCH] clk: canaan: Clear rate fields before reprogramming dividers Date: Thu, 18 Jun 2026 05:50:30 +0100 Message-ID: <20260618045030.12581-1-devnexen@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The rate set_rate helpers perform a read-modify-write on the divider and multiplier registers but only ever OR the new value in, without first masking off the existing field. The first write after reset lands on a zeroed field and looks correct, but any later reprogramming leaves the old bits set: the field becomes the bitwise OR of the previous and new encodings, corrupting the divider or multiplier. Mask off each field before writing the new value so reprogramming a clock to a different rate produces the intended register contents. Fixes: a7b7c7c6c016 ("clk: canaan: Add clock driver for Canaan K230") Signed-off-by: David Carlier --- drivers/clk/clk-k230.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/clk/clk-k230.c b/drivers/clk/clk-k230.c index cfc437038e4e..f34a3e6d3bca 100644 --- a/drivers/clk/clk-k230.c +++ b/drivers/clk/clk-k230.c @@ -2227,6 +2227,7 @@ static int k230_clk_set_rate_mul(struct clk_hw *hw, unsigned long rate, guard(spinlock)(rate_self->lock); mul_reg = readl(rate_self->reg + clk->mul_reg_off); + mul_reg &= ~(rate_self->mul_mask << rate_self->mul_shift); mul_reg |= ((mul - 1) & rate_self->mul_mask) << (rate_self->mul_shift); mul_reg |= BIT(rate_self->write_enable_bit); writel(mul_reg, rate_self->reg + clk->mul_reg_off); @@ -2257,6 +2258,7 @@ static int k230_clk_set_rate_div(struct clk_hw *hw, unsigned long rate, guard(spinlock)(rate_self->lock); div_reg = readl(rate_self->reg + clk->div_reg_off); + div_reg &= ~(rate_self->div_mask << rate_self->div_shift); div_reg |= ((div - 1) & rate_self->div_mask) << (rate_self->div_shift); div_reg |= BIT(rate_self->write_enable_bit); writel(div_reg, rate_self->reg + clk->div_reg_off); @@ -2287,11 +2289,13 @@ static int k230_clk_set_rate_mul_div(struct clk_hw *hw, unsigned long rate, guard(spinlock)(rate_self->lock); div_reg = readl(rate_self->reg + clk->div_reg_off); + div_reg &= ~(rate_self->div_mask << rate_self->div_shift); div_reg |= ((div - 1) & rate_self->div_mask) << (rate_self->div_shift); div_reg |= BIT(rate_self->write_enable_bit); writel(div_reg, rate_self->reg + clk->div_reg_off); mul_reg = readl(rate_self->reg + clk->mul_reg_off); + mul_reg &= ~(rate_self->mul_mask << rate_self->mul_shift); mul_reg |= ((mul - 1) & rate_self->mul_mask) << (rate_self->mul_shift); mul_reg |= BIT(rate_self->write_enable_bit); writel(mul_reg, rate_self->reg + clk->mul_reg_off); -- 2.53.0