[PATCH] i2c: tegra: Use non-HS timings for clock divisor

[PATCH] i2c: tegra: Use non-HS timings for clock divisor

[Akhil R]

Programming the HS timing registers overwrites the local tlow and thigh
values before they are used to calculate the controller clock rate. On
controllers with HS support, this mixes HS timings with the clock divisor
calculation and sets an incorrect clock rate.

Calculate the clock multiplier before the HS register setup overwrites
the selected non-HS timings.

Fixes: 978b3ccbbac3 ("i2c: tegra: Add HS mode support")
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
 drivers/i2c/busses/i2c-tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 76d21bc51c618..6a98432734d37 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -976,6 +976,8 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
 	if (i2c_dev->hw->has_interface_timing_reg && tsu_thd)
 		i2c_writel(i2c_dev, tsu_thd, i2c_dev->hw->regs->interface_timing_1);
 
+	clk_multiplier = (tlow + thigh + 2) * (non_hs_mode + 1);
+
 	/* Write HS mode registers. These will get used only for HS mode*/
 	if (i2c_dev->hw->enable_hs_mode_support) {
 		tlow = i2c_dev->hw->tlow_hs_mode;
@@ -988,8 +990,6 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
 		i2c_writel(i2c_dev, tsu_thd, i2c_dev->hw->regs->hs_interface_timing_1);
 	}
 
-	clk_multiplier = (tlow + thigh + 2) * (non_hs_mode + 1);
-
 	err = clk_set_rate(i2c_dev->div_clk,
 			   t->bus_freq_hz * clk_multiplier);
 	if (err) {

base-commit: 7649ba73f9e7e1e04d0b46213e39c79ae09dd55c
-- 
2.43.0

Re: [PATCH] i2c: tegra: Use non-HS timings for clock divisor

[Jon Hunter]

On 10/11/2026 16:23, Akhil R wrote:
> Programming the HS timing registers overwrites the local tlow and thigh
> values before they are used to calculate the controller clock rate. On
> controllers with HS support, this mixes HS timings with the clock divisor
> calculation and sets an incorrect clock rate.
> 
> Calculate the clock multiplier before the HS register setup overwrites
> the selected non-HS timings.
> 
> Fixes: 978b3ccbbac3 ("i2c: tegra: Add HS mode support")
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> ---
>  drivers/i2c/busses/i2c-tegra.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 76d21bc51c618..6a98432734d37 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -976,6 +976,8 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
>  	if (i2c_dev->hw->has_interface_timing_reg && tsu_thd)
>  		i2c_writel(i2c_dev, tsu_thd, i2c_dev->hw->regs->interface_timing_1);
>  
> +	clk_multiplier = (tlow + thigh + 2) * (non_hs_mode + 1);
> +
>  	/* Write HS mode registers. These will get used only for HS mode*/
>  	if (i2c_dev->hw->enable_hs_mode_support) {
>  		tlow = i2c_dev->hw->tlow_hs_mode;
> @@ -988,8 +990,6 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
>  		i2c_writel(i2c_dev, tsu_thd, i2c_dev->hw->regs->hs_interface_timing_1);
>  	}
>  
> -	clk_multiplier = (tlow + thigh + 2) * (non_hs_mode + 1);
> -
>  	err = clk_set_rate(i2c_dev->div_clk,
>  			   t->bus_freq_hz * clk_multiplier);
>  	if (err) {
> 
> base-commit: 7649ba73f9e7e1e04d0b46213e39c79ae09dd55c


Reviewed-by: Jon Hunter <jonathanh@nvidia.com>

Thanks!
Jon

-- 
nvpublic