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Date: Tue, 20 Mar 2018 18:19:18 -0700 From: Guenter Roeck <linux@...ck-us.net> To: Vladimir Zapolskiy <vz@...ia.com>, Peter Rosin <peda@...ntia.se>, linux-kernel@...r.kernel.org, Ken Chen <chen.kenyy@...entec.com> Cc: Wolfram Sang <wsa@...-dreams.de>, joel@....id.au, linux-i2c@...r.kernel.org Subject: Re: [PATCH 3/3] i2c: mux: pca9541: prepare for PCA9641 support On 03/20/2018 04:17 PM, Vladimir Zapolskiy wrote: > Hi Peter, Ken, > > On 03/20/2018 11:32 AM, Peter Rosin wrote: >> Make the arbitrate and release_bus implementation chip specific. >> > > by chance I took a look at the original implementation done by Ken, and > I would say that this 3/3 change is an overkill as a too generic one. > Is there any next observable extension? And do two abstracted (*arbitrate) > and (*release_bus) cover it well? Probably no. > > At first it would be simpler to add a new chip id field into struct pca9541 > (struct rename would be needed of course), and do a selection of specific > pca9x41_arbitrate() and pca9x41_release_bus() depending on it: > FWIW, I very much prefer Peter's code. I think it is much cleaner. Guenter > ----8<---- > diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c > index 47685eb..a40e6d8 100644 > --- a/drivers/i2c/muxes/i2c-mux-pca9541.c > +++ b/drivers/i2c/muxes/i2c-mux-pca9541.c > @@ -70,8 +70,13 @@ > #define SELECT_DELAY_SHORT 50 > #define SELECT_DELAY_LONG 1000 > > +enum chip_id { > + pca9541, > +}; > + > struct pca9541 { > struct i2c_client *client; > + enum chip_id id; > unsigned long select_timeout; > unsigned long arb_timeout; > }; > @@ -188,10 +193,13 @@ static int pca9541_reg_read(struct i2c_client *client, u8 command) > */ > > /* Release bus. Also reset NTESTON and BUSINIT if it was set. */ > -static void pca9541_release_bus(struct i2c_client *client) > +static void pca9541_release_bus(struct i2c_client *client, enum chip_id id) > { > int reg; > > + if (id != pca9541) > + return; > + > reg = pca9541_reg_read(client, PCA9541_CONTROL); > if (reg >= 0 && !pca9541_busoff(reg) && pca9541_mybus(reg)) > pca9541_reg_write(client, PCA9541_CONTROL, > @@ -235,12 +243,15 @@ static const u8 pca9541_control[16] = { > * 0 : bus not acquired > * 1 : bus acquired > */ > -static int pca9541_arbitrate(struct i2c_client *client) > +static int pca9541_arbitrate(struct i2c_client *client, enum chip_id id) > { > struct i2c_mux_core *muxc = i2c_get_clientdata(client); > struct pca9541 *data = i2c_mux_priv(muxc); > int reg; > > + if (id != pca9541) > + return -EOPNOTSUPP; > + > reg = pca9541_reg_read(client, PCA9541_CONTROL); > if (reg < 0) > return reg; > @@ -318,7 +329,7 @@ static int pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan) > /* force bus ownership after this time */ > > do { > - ret = pca9541_arbitrate(client); > + ret = pca9541_arbitrate(client, data->id); > if (ret) > return ret < 0 ? ret : 0; > > @@ -336,7 +347,7 @@ static int pca9541_release_chan(struct i2c_mux_core *muxc, u32 chan) > struct pca9541 *data = i2c_mux_priv(muxc); > struct i2c_client *client = data->client; > > - pca9541_release_bus(client); > + pca9541_release_bus(client, data->id); > return 0; > } > > @@ -361,7 +372,7 @@ static int pca9541_probe(struct i2c_client *client, > * We have to lock the adapter before releasing the bus. > */ > i2c_lock_adapter(adap); > - pca9541_release_bus(client); > + pca9541_release_bus(client, pca9541); > i2c_unlock_adapter(adap); > > /* Create mux adapter */ > @@ -377,6 +388,7 @@ static int pca9541_probe(struct i2c_client *client, > > data = i2c_mux_priv(muxc); > data->client = client; > + data->id = pca9541; > > i2c_set_clientdata(client, muxc); > > ----8<---- > > >> Signed-off-by: Peter Rosin <peda@...ntia.se> >> --- >> drivers/i2c/muxes/i2c-mux-pca9541.c | 62 +++++++++++++++++++++++++++---------- >> 1 file changed, 45 insertions(+), 17 deletions(-) >> > > The change above is trivial and it does not cancel any further > extensions similar to your idea, the open question is if there > is a demand right at the moment. > >> diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c >> index 47685eb4e0e9..cac629e36bf8 100644 >> --- a/drivers/i2c/muxes/i2c-mux-pca9541.c >> +++ b/drivers/i2c/muxes/i2c-mux-pca9541.c >> @@ -23,6 +23,7 @@ >> #include <linux/i2c-mux.h> >> #include <linux/jiffies.h> >> #include <linux/module.h> >> +#include <linux/of_device.h> >> #include <linux/platform_data/pca954x.h> >> #include <linux/slab.h> >> >> @@ -70,26 +71,22 @@ >> #define SELECT_DELAY_SHORT 50 >> #define SELECT_DELAY_LONG 1000 >> >> -struct pca9541 { >> - struct i2c_client *client; >> - unsigned long select_timeout; >> - unsigned long arb_timeout; >> +enum chip_name { > > chip_name sound like a string storage, chip_id might be better here. > >> + pca9541, >> }; >> > > -- > With best wishes, > Vladimir >
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