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From: Vladimir Zapolskiy <vz@mleia.com>
To: Peter Rosin <peda@axentia.se>,
	linux-kernel@vger.kernel.org, Ken Chen <chen.kenyy@inventec.com>
Cc: Guenter Roeck <linux@roeck-us.net>,
	Wolfram Sang <wsa@the-dreams.de>,
	joel@jms.id.au, linux-i2c@vger.kernel.org
Subject: Re: [PATCH 3/3] i2c: mux: pca9541: prepare for PCA9641 support
Date: Wed, 21 Mar 2018 01:17:39 +0200	[thread overview]
Message-ID: <bc464354-660a-00ed-e713-eec987407695@mleia.com> (raw)
In-Reply-To: <20180320093200.19179-4-peda@axentia.se>

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:

----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@axentia.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

  parent reply	other threads:[~2018-03-20 23:17 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-20  6:19 [PATCH linux dev-4.16 v2] i2c: muxes: pca9641: new driver Ken Chen
2018-03-20  6:34 ` Joel Stanley
2018-03-20  9:31 ` Peter Rosin
2018-03-20  9:31   ` [PATCH 1/3] i2c: mux: pca9541: use the BIT macro Peter Rosin
2018-03-20 13:18     ` Guenter Roeck
2018-03-20 23:25     ` Vladimir Zapolskiy
2018-03-20  9:31   ` [PATCH 2/3] i2c: mux: pca9541: namespace cleanup Peter Rosin
2018-03-20 13:20     ` Guenter Roeck
2018-03-20 21:48       ` Peter Rosin
2018-03-20 21:57         ` Guenter Roeck
2018-03-20 23:24     ` Vladimir Zapolskiy
2018-03-21  5:53       ` Peter Rosin
2018-03-21  6:54         ` Vladimir Zapolskiy
2018-03-21  7:35           ` Peter Rosin
2018-03-20  9:32   ` [PATCH 3/3] i2c: mux: pca9541: prepare for PCA9641 support Peter Rosin
2018-03-20 13:22     ` Guenter Roeck
2018-03-20 23:17     ` Vladimir Zapolskiy [this message]
2018-03-21  1:19       ` Guenter Roeck
2018-03-21  7:01         ` Vladimir Zapolskiy
2018-03-21  8:09           ` Peter Rosin
2018-03-21  7:05     ` Vladimir Zapolskiy
2018-04-11  9:37   ` [PATCH linux dev-4.16 v2] i2c: muxes: pca9641: new driver Peter Rosin
2018-04-13  6:59     ` ChenKenYY 陳永營 TAO
2018-04-13  7:27       ` Peter Rosin
2018-04-16  7:37         ` ChenKenYY 陳永營 TAO

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