linux-kernel - Re: [PATCH v3 07/15] media: i2c: ds90ub960: Add support for I2C_RX

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Message-ID: <Z1Fk7jRVQJZzsTQp@smile.fi.intel.com>
Date: Thu, 5 Dec 2024 10:31:42 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Hans Verkuil <hverkuil-cisco@...all.nl>,
	Jai Luthra <jai.luthra@...asonboard.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 07/15] media: i2c: ds90ub960: Add support for I2C_RX_ID

On Wed, Dec 04, 2024 at 01:05:21PM +0200, Tomi Valkeinen wrote:
> Normally the driver accesses both the RX and the TX port registers via a
> paging mechanism: one register is used to select the page (i.e. the
> port), which dictates the port used when accessing the port specific
> registers.
> 
> The downside to this is that while debugging it's almost impossible to
> access the port specific registers from the userspace, as the driver can
> change the page at any moment.
> 
> The hardware supports another access mechanism: using the I2C_RX_ID
> registers (one for each RX port), i2c addresses can be chosen which,
> when accessed, will always use the specific port's registers, skipping
> the paging mechanism.
> 
> The support is only for the RX port, but it has proven very handy while
> debugging and testing. So let's add the code for this, but hide it
> behind a disabled define.

...

>  #define MHZ(v) ((u32)((v) * 1000000U))

Missed HZ_PER_MHZ from previous patch?

...

> +#ifdef UB960_DEBUG_I2C_RX_ID
> +	for (unsigned int i = 0; i < 4; i++)

Should it use _MAX_RX_NPORTS instead of 4?

> +		ub960_write(priv, UB960_SR_I2C_RX_ID(i),
> +			    (UB960_DEBUG_I2C_RX_ID + i) << 1);
> +#endif

-- 
With Best Regards,
Andy Shevchenko