linux-kernel - Re: [PATCH v1 2/3] auxdisplay: ht16k33: Make use of device_get_match

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Message-ID: <be203dfd290e67c8ce74d11c5c9478a4@protonic.nl>
Date:   Tue, 21 Feb 2023 17:10:00 +0100
From:   Robin van der Gracht <robin@...tonic.nl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
        Raul E Rangel <rrangel@...omium.org>,
        Wolfram Sang <wsa@...nel.org>, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-usb@...r.kernel.org,
        Miguel Ojeda <ojeda@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v1 2/3] auxdisplay: ht16k33: Make use of
 device_get_match_data()

Hello Andy,

On 2023-02-21 14:40, Andy Shevchenko wrote:
> On Tue, Feb 21, 2023 at 03:33:06PM +0200, Andy Shevchenko wrote:
>> Switching to use device_get_match_data() helps getting of
>> i2c_of_match_device() API.
> 
> ...
> 
>> -	id = i2c_of_match_device(dev->driver->of_match_table, client);
>> -	if (id)
>> -		priv->type = (uintptr_t)id->data;
>> +	priv->type = (uintptr_t)device_get_match_data(dev);
> 
> Looking closer the I²C ID table should provide DISP_MATRIX to keep 
> default and
> this needs to be not dropped.
> 
> So, the question is what to do with unknown type then, return -EINVAL 
> from
> probe()?

If you leave out your addition of the DISP_UNKNOWN type, the default 
type will
be DISP_MATRIX if no match is found, which is as it is now.

In that case the following change should suffice:

@@ -713,7 +715,6 @@ static int ht16k33_seg_probe(struct device *dev, 
struct ht16k33_priv *priv,
  static int ht16k33_probe(struct i2c_client *client)
  {
      struct device *dev = &client->dev;
-    const struct of_device_id *id;
      struct ht16k33_priv *priv;
      uint32_t dft_brightness;
      int err;
@@ -728,9 +729,8 @@ static int ht16k33_probe(struct i2c_client *client)
          return -ENOMEM;

      priv->client = client;
-    id = i2c_of_match_device(dev->driver->of_match_table, client);
-    if (id)
-        priv->type = (uintptr_t)id->data;
+    priv->type = (uintptr_t)device_get_match_data(dev);
+
      i2c_set_clientdata(client, priv);

      err = ht16k33_initialize(priv);

Or do you think falling back to DISP_MATRIX if no match is found is 
wrong?

Kind regards,
Robin