2013-03-19 21:33:39

by Henrik Rydberg

[permalink] [raw]
Subject: Re: [PATCH 6/7] HID: multitouch: append " Pen" to the name of the stylus input

Hi Benjamin,

> This is not just cosmetics, it can help to write udev and X.org
> rules.
>
> Signed-off-by: Benjamin Tissoires <[email protected]>
> ---
> drivers/hid/hid-multitouch.c | 24 +++++++++++++++++++++++-
> 1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index d89f0eb..faeec95 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -44,6 +44,7 @@
> #include <linux/slab.h>
> #include <linux/usb.h>
> #include <linux/input/mt.h>
> +#include <linux/string.h>
>
>
> MODULE_AUTHOR("Stephane Chatty <[email protected]>");
> @@ -371,6 +372,15 @@ static int mt_pen_input_mapping(struct hid_device *hdev, struct hid_input *hi,
> unsigned long **bit, int *max)
> {
> struct mt_device *td = hid_get_drvdata(hdev);
> + char *name;
> +
> + if (hi->input->name == hdev->name) {
> + name = kzalloc(sizeof(hdev->name) + 5, GFP_KERNEL);
> + if (name) {
> + sprintf(name, "%s Pen", hdev->name);
> + hi->input->name = name;
> + }
> + }

Why not simply duplicate the the string? This kind of magic sharing is
not really helping. Also, for multi input devices, the assumptions in
hidinput_allocate() seem to be the culprit. Perhaps the fix should be
there instead.

>
> td->pen_report_id = field->report->id;
>
> @@ -914,6 +924,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
> int ret, i;
> struct mt_device *td;
> struct mt_class *mtclass = mt_classes; /* MT_CLS_DEFAULT */
> + struct hid_input *hi;
>
> for (i = 0; mt_classes[i].name ; i++) {
> if (id->driver_data == mt_classes[i].name) {
> @@ -964,7 +975,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>
> ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
> if (ret)
> - goto fail;
> + goto hid_fail;
>
> ret = sysfs_create_group(&hdev->dev.kobj, &mt_attribute_group);
>
> @@ -976,6 +987,10 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>
> return 0;
>
> +hid_fail:
> + list_for_each_entry(hi, &hdev->inputs, list)
> + if (hi->input->name != hdev->name)
> + kfree(hi->input->name);
> fail:
> kfree(td->fields);
> kfree(td);
> @@ -1020,8 +1035,15 @@ static int mt_resume(struct hid_device *hdev)
> static void mt_remove(struct hid_device *hdev)
> {
> struct mt_device *td = hid_get_drvdata(hdev);
> + struct hid_input *hi;
> +
> sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
> hid_hw_stop(hdev);
> +
> + list_for_each_entry(hi, &hdev->inputs, list)
> + if (hi->input->name != hdev->name)
> + kfree(hi->input->name);
> +
> kfree(td);
> hid_set_drvdata(hdev, NULL);
> }
> --
> 1.8.1.2
>

Thanks,
Henrik


2013-03-20 14:43:21

by Benjamin Tissoires

[permalink] [raw]
Subject: Re: [PATCH 6/7] HID: multitouch: append " Pen" to the name of the stylus input

On 03/19/2013 10:38 PM, Henrik Rydberg wrote:
> Hi Benjamin,
>
>> This is not just cosmetics, it can help to write udev and X.org
>> rules.
>>
>> Signed-off-by: Benjamin Tissoires <[email protected]>
>> ---
>> drivers/hid/hid-multitouch.c | 24 +++++++++++++++++++++++-
>> 1 file changed, 23 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
>> index d89f0eb..faeec95 100644
>> --- a/drivers/hid/hid-multitouch.c
>> +++ b/drivers/hid/hid-multitouch.c
>> @@ -44,6 +44,7 @@
>> #include <linux/slab.h>
>> #include <linux/usb.h>
>> #include <linux/input/mt.h>
>> +#include <linux/string.h>
>>
>>
>> MODULE_AUTHOR("Stephane Chatty <[email protected]>");
>> @@ -371,6 +372,15 @@ static int mt_pen_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> unsigned long **bit, int *max)
>> {
>> struct mt_device *td = hid_get_drvdata(hdev);
>> + char *name;
>> +
>> + if (hi->input->name == hdev->name) {
>> + name = kzalloc(sizeof(hdev->name) + 5, GFP_KERNEL);
>> + if (name) {
>> + sprintf(name, "%s Pen", hdev->name);
>> + hi->input->name = name;
>> + }
>> + }
>
> Why not simply duplicate the the string? This kind of magic sharing is
> not really helping. Also, for multi input devices, the assumptions in
> hidinput_allocate() seem to be the culprit. Perhaps the fix should be
> there instead.

Yes, hidinput_allocate() clearly steals the reference here. However,
fixing this in hid-core would not be simpler: some drivers (ntrig does
at least) assume that there is no need to free input->name, which means
that:
- either we need to fix each individual driver
- either we introduce some kind of mechanism in order not to free "const
char *" declarations like it happens in ntrig.

In v2, I'll just realloc for each input the input->name, and then if the
pen is here, then it will realloc the new name.

Cheers,
Benjamin

>
>>
>> td->pen_report_id = field->report->id;
>>
>> @@ -914,6 +924,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>> int ret, i;
>> struct mt_device *td;
>> struct mt_class *mtclass = mt_classes; /* MT_CLS_DEFAULT */
>> + struct hid_input *hi;
>>
>> for (i = 0; mt_classes[i].name ; i++) {
>> if (id->driver_data == mt_classes[i].name) {
>> @@ -964,7 +975,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>>
>> ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
>> if (ret)
>> - goto fail;
>> + goto hid_fail;
>>
>> ret = sysfs_create_group(&hdev->dev.kobj, &mt_attribute_group);
>>
>> @@ -976,6 +987,10 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>>
>> return 0;
>>
>> +hid_fail:
>> + list_for_each_entry(hi, &hdev->inputs, list)
>> + if (hi->input->name != hdev->name)
>> + kfree(hi->input->name);
>> fail:
>> kfree(td->fields);
>> kfree(td);
>> @@ -1020,8 +1035,15 @@ static int mt_resume(struct hid_device *hdev)
>> static void mt_remove(struct hid_device *hdev)
>> {
>> struct mt_device *td = hid_get_drvdata(hdev);
>> + struct hid_input *hi;
>> +
>> sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
>> hid_hw_stop(hdev);
>> +
>> + list_for_each_entry(hi, &hdev->inputs, list)
>> + if (hi->input->name != hdev->name)
>> + kfree(hi->input->name);
>> +
>> kfree(td);
>> hid_set_drvdata(hdev, NULL);
>> }
>> --
>> 1.8.1.2
>>
>
> Thanks,
> Henrik
>