[PATCH RFC 5/5] drm/i2c: add tda998x/tda9950 CEC driver

[Russell King - ARM Linux]

On Fri, Aug 12, 2016 at 04:38:04PM +0200, Hans Verkuil wrote:
> On 08/12/2016 04:15 PM, Russell King wrote:
> >Add a CEC driver for the TDA9950, which is a stand-alone I2C CEC device.
> >The TDA9950 contains a command processor which handles retransmissions
> >and the low level bus protocol.  The driver just has to read and write
> >the messages, and handle error conditions.
> >
> >Signed-off-by: Russell King <rmk+kernel at armlinux.org.uk>
> >---
> > drivers/gpu/drm/i2c/Kconfig           |   5 +
> > drivers/gpu/drm/i2c/Makefile          |   1 +
> > drivers/gpu/drm/i2c/tda9950.c         | 514 ++++++++++++++++++++++++++++++++++
> > include/linux/platform_data/tda9950.h |  15 +
> > 4 files changed, 535 insertions(+)
> > create mode 100644 drivers/gpu/drm/i2c/tda9950.c
> > create mode 100644 include/linux/platform_data/tda9950.h
> >
> 
> <snip>
> 
> >+static int tda9950_cec_adap_log_addr(struct cec_adapter *adap, u8 addr)
> >+{
> >+	struct tda9950_priv *priv = adap->priv;
> >+	u16 addresses;
> >+	u8 buf[2];
> >+
> >+	if (addr == CEC_LOG_ADDR_INVALID)
> >+		addresses = priv->addresses = BIT(15);
> 
> I saw this in patch 4/5 as well: why set bit 15? I would expect that this
> is just set to 0. And priv->addresses doesn't seem to be used anywhere.

It's needed to be set so that the hardware receives messages sent
to the broadcast (15) address.

> >+	else
> >+		addresses = priv->addresses |= BIT(addr);

For the second point, read this line, paying close attention to the |=.

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