Hi Robert > For the existing devices you can override the ACPI tables using initrd. > https://www.kernel.org/doc/Documentation/acpi/initrd_table_override.txt > > There is some work being done that will allow to amend (no need to > completely override) the ACPI tables with custom data. > https://lkml.org/lkml/2015/6/18/947 I see. I was under the impression that modifying the DSDT is generally frowned upon and will result in a tainted kernel. > Device tree already has support for overlays. > > Giving this I think that we should keep the driver as simple as possible. I absolutely agree. However, as long as there is no alternative way to pass the necessary parameters, a driver will not work on all machines, particularly those that were designed to be shipped with Microsoft Windows. I suspect that vendors will be reluctant to change their (UEFI) BIOSes to accommodate full Linux support in such devices. > I will come back with the info on the touch id after I check the docs. Thanks. > axis swapping, mirroring sound like a good addon. > there is currently support for width, height, number of touch points and > firmware name Those features are fairly easy to implement, and thanks to the great work by the linux-input team, even finger tracking is not difficult to integrate. Some example code is included below. > IMHO it's not a good idea to do the config using sysfs. You are probably right, yes. In the meantime, I had a different idea. Instead of passing the panel and firmware parameters (width, height, number of touch areas, mirroring, swapping, tracking support) through device_property_read, they could be contained in the firmware, in a special header. As practically every single device seems to require its own firmware, users and platform builders would need to obtain it anyway. Why not include all the information the driver requires with the firmware image itself? Reading the firmware name from the DSDT/DT like all the other parameters is an option, of course. However... If you have, let's say, 100 different devices on the market, all with different firmware, you'd have to install 100 different firmware images to make automatic detection and device startup possible. This doesn't seem very reasonable. On the other hand, just logging an error that a specific firmware is required and requiring the user to manually download and install that firmware isn't much better than logging vendor/device data from the DMI, then provide a tool or website that provides the appropriate firmware for that device. Another obvious approach would be device quirks. Many drivers in the Linux kernel follow this approach, but I'm not sure if it's a preferable solution. Again, assuming there are a 100 different devices with a limited DSDT out there, one would need 100 different device quirks. That number is, obviously, purely hypothetical. But I hope you get the picture. Code example: Swapping, mirroring and finger tracking support (error checking omitted for simplicity): /* 0 = unlimited distance */ #define MAX_DISTANCE 0 #define MAX_CONTACTS 10 struct gsl_ts_data { struct input_dev *input; /* ... */ unsigned int x_max; unsigned int y_max; unsigned int multi_touches; bool x_reversed; bool y_reversed; bool xy_swapped; bool soft_tracking; }; static int gsl_ts_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct gsl_ts_data *ts; /* ... */ ts = devm_kzalloc(&client->dev, sizeof(struct gsl_ts_data), GFP_KERNEL); ts->input = devm_input_allocate_device(&client->dev); if (ts->soft_tracking) { input_mt_init_slots(ts->input, ts->multi_touches, INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED | INPUT_MT_TRACK); } else { input_mt_init_slots(ts->input, ts->multi_touches, INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED); } /* ... */ } static void gsl_ts_mt_event(struct gsl_ts_data *ts, u8 *buf) { size_t i; struct input_mt_pos positions[MAX_CONTACTS]; int slots[MAX_CONTACTS]; /* ... */ if (num_touches > MAX_CONTACTS) { num_touches = MAX_CONTACTS; } for (i = 0; i < num_touches; i++) { /* ... */ if (ts->xy_swapped) { swap(x, y); } if (ts->x_reversed) { x = ts->x_max - x; } if (ts->y_reversed) { y = ts->y_max - y; } positions[i].x = x; positions[i].y = y; if (!ts->soft_tracking) { slots[i] = id; } } if (ts->soft_tracking) { #if LINUX_VERSION_CODE < KERNEL_VERSION(4,0,0) rc = input_mt_assign_slots(input, slots, positions, touches); #else rc = input_mt_assign_slots(input, slots, positions, touches, MAX_DISTANCE); #endif if (rc < 0) { dev_err(dev, "%s: input_mt_assign_slots returned %d\n", __func__, rc); return; } } for (i = 0; i < num_touches; i++) { input_mt_slot(input, slots[i]); input_mt_report_slot_state(input, MT_TOOL_FINGER, true); input_report_abs(input, ABS_MT_POSITION_X, positions[i].x); input_report_abs(input, ABS_MT_POSITION_Y, positions[i].y); } input_mt_sync_frame(input); input_sync(input); } -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
