On 2018-10-03 17:19, Luca Ceresoli wrote:
> From: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx>
>
> i2c-mux instantiates one i2c_algorithm for each downstream adapter.
> However these algorithms are all identical, depending only on the
> parent adapter.
>
> Avoid duplication by hoisting the i2c_algorithm from the adapters to
> the i2c_mux_core object, and reuse it in all the adapters.
Ouch, while I like the concept of having one i2c_algorithm per mux,
this patch is not working. Various i2c-mux drivers set the
muxc->mux_locked variable *after* the i2c_mux_alloc call, and this
patch breaks such use.
So, the patch needs some reworking. Sorry for not noticing this
earlier.
Cheers,
Peter
> Cc: Peter Rosin <peda@xxxxxxxxxx>
> Signed-off-by: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx>
>
> ---
>
> Changes v2 -> v3:
> - fix coding style of comment when moving it (Peter Rosin)
> - move the 'algo' member between parent and dev (Peter Rosin)
>
> Changes v1 -> v2:
> - include i2c.h (fixes build failure on i2c-mux-ltc4306)
> ---
> drivers/i2c/i2c-mux.c | 38 +++++++++++++++++++-------------------
> include/linux/i2c-mux.h | 2 ++
> 2 files changed, 21 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
> index f330690b4125..6ac23004fb2a 100644
> --- a/drivers/i2c/i2c-mux.c
> +++ b/drivers/i2c/i2c-mux.c
> @@ -30,7 +30,6 @@
> /* multiplexer per channel data */
> struct i2c_mux_priv {
> struct i2c_adapter adap;
> - struct i2c_algorithm algo;
> struct i2c_mux_core *muxc;
> u32 chan_id;
> };
> @@ -263,6 +262,24 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
> muxc->deselect = deselect;
> muxc->max_adapters = max_adapters;
>
> + /*
> + * Need to do algo dynamically because we don't know ahead of
> + * time what sort of physical adapter we'll be dealing with.
> + */
> + if (parent->algo->master_xfer) {
> + if (muxc->mux_locked)
> + muxc->algo.master_xfer = i2c_mux_master_xfer;
> + else
> + muxc->algo.master_xfer = __i2c_mux_master_xfer;
> + }
> + if (parent->algo->smbus_xfer) {
> + if (muxc->mux_locked)
> + muxc->algo.smbus_xfer = i2c_mux_smbus_xfer;
> + else
> + muxc->algo.smbus_xfer = __i2c_mux_smbus_xfer;
> + }
> + muxc->algo.functionality = i2c_mux_functionality;
> +
> return muxc;
> }
> EXPORT_SYMBOL_GPL(i2c_mux_alloc);
> @@ -301,28 +318,11 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
> priv->muxc = muxc;
> priv->chan_id = chan_id;
>
> - /* Need to do algo dynamically because we don't know ahead
> - * of time what sort of physical adapter we'll be dealing with.
> - */
> - if (parent->algo->master_xfer) {
> - if (muxc->mux_locked)
> - priv->algo.master_xfer = i2c_mux_master_xfer;
> - else
> - priv->algo.master_xfer = __i2c_mux_master_xfer;
> - }
> - if (parent->algo->smbus_xfer) {
> - if (muxc->mux_locked)
> - priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
> - else
> - priv->algo.smbus_xfer = __i2c_mux_smbus_xfer;
> - }
> - priv->algo.functionality = i2c_mux_functionality;
> -
> /* Now fill out new adapter structure */
> snprintf(priv->adap.name, sizeof(priv->adap.name),
> "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
> priv->adap.owner = THIS_MODULE;
> - priv->adap.algo = &priv->algo;
> + priv->adap.algo = &muxc->algo;
> priv->adap.algo_data = priv;
> priv->adap.dev.parent = &parent->dev;
> priv->adap.retries = parent->retries;
> diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
> index bd74d5706f3b..3d89600d5a9e 100644
> --- a/include/linux/i2c-mux.h
> +++ b/include/linux/i2c-mux.h
> @@ -28,9 +28,11 @@
> #ifdef __KERNEL__
>
> #include <linux/bitops.h>
> +#include <linux/i2c.h>
>
> struct i2c_mux_core {
> struct i2c_adapter *parent;
> + struct i2c_algorithm algo;
> struct device *dev;
> unsigned int mux_locked:1;
> unsigned int arbitrator:1;
>
