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SubjectRe: [PATCH v1 07/11] ti948: Add sysfs node for alive attribute
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Hi Laurent,

On 11/06/2019 19:11, Laurent Pinchart wrote:
> Hi Michael,
>
> Thank you for the patch.

My pleasure, and thank you for the feedback!

> On Tue, Jun 11, 2019 at 03:04:08PM +0100, Michael Drake wrote:
>> This may be used by userspace to determine the state
>> of the device.
>
> Why is this needed ? Userspace shouldn't even be aware that this device
> exists.

The display (containing the ti948) could be unplugged. (See my
response to the feedback on the previous commit in the series.)

If you can suggest a better or more standard way of doing this
I would be very happy to learn of it.

>> Signed-off-by: Michael Drake <michael.drake@codethink.co.uk>
>> Cc: Patrick Glaser <pglaser@tesla.com>
>> Cc: Nate Case <ncase@tesla.com>
>> ---
>> drivers/gpu/drm/bridge/ti948.c | 28 ++++++++++++++++++++++++++--
>> 1 file changed, 26 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/ti948.c b/drivers/gpu/drm/bridge/ti948.c
>> index b5c766711c4b..b624eaeabb43 100644
>> --- a/drivers/gpu/drm/bridge/ti948.c
>> +++ b/drivers/gpu/drm/bridge/ti948.c
>> @@ -412,6 +412,16 @@ static void ti948_alive_check(struct work_struct *work)
>> schedule_delayed_work(&ti948->alive_check, TI948_ALIVE_CHECK_DELAY);
>> }
>>
>> +static ssize_t alive_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct ti948_ctx *ti948 = ti948_ctx_from_dev(dev);
>> +
>> + return scnprintf(buf, PAGE_SIZE, "%u\n", (unsigned int)ti948->alive);
>> +}
>> +
>> +static DEVICE_ATTR_RO(alive);
>> +
>> static int ti948_pm_resume(struct device *dev)
>> {
>> struct ti948_ctx *ti948 = ti948_ctx_from_dev(dev);
>> @@ -614,17 +624,31 @@ static int ti948_probe(struct i2c_client *client,
>>
>> i2c_set_clientdata(client, ti948);
>>
>> + ret = device_create_file(&client->dev, &dev_attr_alive);
>> + if (ret) {
>> + dev_err(&client->dev, "Could not create alive attr\n");
>> + return ret;
>> + }
>> +
>> ret = ti948_pm_resume(&client->dev);
>> - if (ret != 0)
>> - return -EPROBE_DEFER;
>> + if (ret != 0) {
>> + ret = -EPROBE_DEFER;
>> + goto error;
>> + }
>>
>> dev_info(&ti948->i2c->dev, "End probe (addr: %x)\n", ti948->i2c->addr);
>>
>> return 0;
>> +
>> +error:
>> + device_remove_file(&client->dev, &dev_attr_alive);
>> + return ret;
>> }
>>
>> static int ti948_remove(struct i2c_client *client)
>> {
>> + device_remove_file(&client->dev, &dev_attr_alive);
>> +
>> return ti948_pm_suspend(&client->dev);
>> }
>>
>

--
Michael Drake https://www.codethink.co.uk/

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