linux-kernel - Re: [PATCH] i2c: stm32f7: do not backup read-only PECR register

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Message-ID: <5b19cf9c-9556-09c9-929d-0c396f689521@st.com>
Date:   Mon, 9 Mar 2020 15:52:20 +0100
From:   Pierre Yves MORDRET <pierre-yves.mordret@...com>
To:     Alain Volmat <alain.volmat@...com>, <wsa@...-dreams.de>
CC:     <alexandre.torgue@...com>, <linux-i2c@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <fabrice.gasnier@...com>
Subject: Re: [PATCH] i2c: stm32f7: do not backup read-only PECR register

Hi Alain

Look good for me

Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@...com>

Regards

On 3/5/20 1:59 PM, Alain Volmat wrote:
> The PECR register provides received packet computed PEC value. 
> It makes no sense restoring its value after a reset, and anyway,
> as read-only register it cannot be restored.
> 
> Fixes: ea6dd25deeb5 ("i2c: stm32f7: add PM_SLEEP suspend/resume support")
> Signed-off-by: Alain Volmat <alain.volmat@...com>
> ---
>  drivers/i2c/busses/i2c-stm32f7.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index 378956ac6d1d..4d7401d62b71 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -176,7 +176,6 @@
>   * @cr2: Control register 2
>   * @oar1: Own address 1 register
>   * @oar2: Own address 2 register
> - * @pecr: PEC register
>   * @tmgr: Timing register
>   */
>  struct stm32f7_i2c_regs {
> @@ -184,7 +183,6 @@ struct stm32f7_i2c_regs {
>  	u32 cr2;
>  	u32 oar1;
>  	u32 oar2;
> -	u32 pecr;
>  	u32 tmgr;
>  };
>  
> @@ -2146,7 +2144,6 @@ static int stm32f7_i2c_regs_backup(struct stm32f7_i2c_dev *i2c_dev)
>  	backup_regs->cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);
>  	backup_regs->oar1 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR1);
>  	backup_regs->oar2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR2);
> -	backup_regs->pecr = readl_relaxed(i2c_dev->base + STM32F7_I2C_PECR);
>  	backup_regs->tmgr = readl_relaxed(i2c_dev->base + STM32F7_I2C_TIMINGR);
>  
>  	pm_runtime_put_sync(i2c_dev->dev);
> @@ -2178,7 +2175,6 @@ static int stm32f7_i2c_regs_restore(struct stm32f7_i2c_dev *i2c_dev)
>  	writel_relaxed(backup_regs->cr2, i2c_dev->base + STM32F7_I2C_CR2);
>  	writel_relaxed(backup_regs->oar1, i2c_dev->base + STM32F7_I2C_OAR1);
>  	writel_relaxed(backup_regs->oar2, i2c_dev->base + STM32F7_I2C_OAR2);
> -	writel_relaxed(backup_regs->pecr, i2c_dev->base + STM32F7_I2C_PECR);
>  
>  	pm_runtime_put_sync(i2c_dev->dev);
>  
>