lkml.org 
[lkml]   [2023]   [Feb]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v1 2/3] auxdisplay: ht16k33: Make use of device_get_match_data()
On 2023-02-21 18:48, Andy Shevchenko wrote:
> On Tue, Feb 21, 2023 at 05:10:00PM +0100, Robin van der Gracht wrote:
>> 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?
>
> First of all, the I²C ID table should actually use DISP_MATRIX.
>
> Second, there are two points:
>
> - It would be nice to check if the OF ID table doesn't provide a
> setting
> (shouldn't we try I²C ID table and then, if still nothing, bail out?)
>
> - The I²C ID table can be extended in the future with another entry
> which
> may want to have different default

For my understanding, please correct me if I'm wrong;

For all methods of instantiation during ht16k33 probe,
i2c_of_match_device()
matches the compatible strings in the OF ID table due to a call to
i2c_of_match_device_sysfs().

device_get_match_data() only matches the compatible strings in the OF ID
table for devicetree instantiation because of_match_device() won't match
is there is no actual of_node.

So with only device_get_match_data() and a non devicetree instantiation,
priv->type will always be (uintptr_t)NULL = 0 = DISP_MATRIX.

Which effectively breaks i.e. user-space instantiation for other display
types which now do work due to i2c_of_match_device().
(so my suggestion above is not sufficient).

Are you proposing extending and searching the I2C ID table to work
around that?

Kind regards,

--
Robin van der Gracht
Protonic Holland
Factorij 36
1689AL Zwaag
+31 (0)229 212928
https://www.protonic.nl

\
 
 \ /
  Last update: 2023-03-27 00:32    [W:0.056 / U:0.148 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site