linux-kernel - Re: [PATCH net-next v6 1/6] ptp: clockmatrix: support 32-bit address space

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Date:   Tue, 5 Dec 2023 09:24:29 +0000
From:   Simon Horman <horms@...nel.org>
To:     Min Li <lnimi@...mail.com>
Cc:     richardcochran@...il.com, lee@...nel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Min Li <min.li.xe@...esas.com>
Subject: Re: [PATCH net-next v6 1/6] ptp: clockmatrix: support 32-bit address
 space

On Thu, Nov 30, 2023 at 01:46:29PM -0500, Min Li wrote:
> From: Min Li <min.li.xe@...esas.com>
> 
> We used to assume 0x2010xxxx address. Now that
> we need to access 0x2011xxxx address, we need
> to support read/write the whole 32-bit address space.
> 
> Signed-off-by: Min Li <min.li.xe@...esas.com>

...

> diff --git a/drivers/ptp/ptp_clockmatrix.c b/drivers/ptp/ptp_clockmatrix.c
> index f6f9d4adce04..f8556627befa 100644
> --- a/drivers/ptp/ptp_clockmatrix.c
> +++ b/drivers/ptp/ptp_clockmatrix.c
> @@ -41,8 +41,8 @@ module_param(firmware, charp, 0);
>  static int _idtcm_adjfine(struct idtcm_channel *channel, long scaled_ppm);
>  
>  static inline int idtcm_read(struct idtcm *idtcm,
> -			     u16 module,
> -			     u16 regaddr,
> +			     u32 module,
> +			     u32 regaddr,
>  			     u8 *buf,
>  			     u16 count)
>  {
> @@ -50,8 +50,8 @@ static inline int idtcm_read(struct idtcm *idtcm,
>  }
>  
>  static inline int idtcm_write(struct idtcm *idtcm,
> -			      u16 module,
> -			      u16 regaddr,
> +			      u32 module,
> +			      u32 regaddr,
>  			      u8 *buf,
>  			      u16 count)
>  {

Hi Min Li,

My understanding of Paolo's review of v5 was that it would be cleaner to:

1. Leave the type of the module parameter as u16
2. Update the type of the regaddr parameter to u32

And...

...

> @@ -553,11 +554,11 @@ static int _sync_pll_output(struct idtcm *idtcm,
>  	val = SYNCTRL1_MASTER_SYNC_RST;
>  
>  	/* Place master sync in reset */
> -	err = idtcm_write(idtcm, 0, sync_ctrl1, &val, sizeof(val));
> +	err = idtcm_write(idtcm, sync_ctrl1, 0, &val, sizeof(val));
>  	if (err)
>  		return err;
>  
> -	err = idtcm_write(idtcm, 0, sync_ctrl0, &sync_src, sizeof(sync_src));
> +	err = idtcm_write(idtcm, sync_ctrl0, 0, &sync_src, sizeof(sync_src));
>  	if (err)
>  		return err;
>  

... avoid the need for changes like the two above.

As it is the meaning of module and regaddr are subtly reversed.
If that is intentional then it really ought to be at least stated
in the patch. And, IMHO, ideally a separate patch.

As it is, reversing the meaning of these parameters seems
to add extra churn to this patch.