Recently I was Trying to work with Qualcomm platform device. I was looking at Flow of touchscreen hbtp_input device driver, the driver is getting registered and calling init function but it doesn't call probe function.Does drivers work without probe functions?
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I am trying to understand first sentence of the commit message.
It says, when a new device whose new driver is available in kernel is plugged in then the new drivers probe will be called but driver core will attach generic driver to the new device.
My question if the new driver probe called when new device plugged in then how this new device will be attached to the generic driver.
Can you guide me to understand this behavior in the kernel source.
We have device ""FT245R USB FIFO" USB to Seriel for communication from Windows 10 using D2xx driver.
FT_OpenEx() API works without any issue. But whenever user unplug/plug new USB device(Mass storage device) , during that time FT_OpenEx() API failed to execute, so handle invalid and our data communication interepted. Could you let us know what can I do further to resolve this issue ?
Note: I have opened handle using following command FT_OpenEx("FT245R USB FIFO", FT_OPEN_BY_DESCRIPTION, &handle), I open it everytime, whenever I need to talk with communication device. tried with seriel number of the device , but still communication fails when unplug/plug other USB device.
I have a device driver with misc_register() API being called to create a serial device. Now, I want to call misc_deregister() because the device does not function any more due to hardware change (for example removal of cable of the serial port). Now the application has opened this device and performing operations on it, so there is an open file descriptor for this device.
I want to know if the driver wait for the application to call release (or close() API) on the device before calling misc_deregister()? Or can the driver call misc_deregister() and then it can still receive a (last) release callback?
I am modifying a monitor controller for a prototype. It would be convenient to send commands to the prototype using DDC/CI. In Windows, I can't find an obvious way to send a DDC/CI command to a "display dependent device".
The Monitor Configuration API can send virtual control panel commands, but it does not give access to display dependent devices (which would have an I2C address other than 0x6e).
Nicomsoft's WinI2C/DDC product seems to give access to a display dependent device, but it is end-of-life. I would prefer not to build a dependency on an end-of-life product.
NVIDIA's NVAPI has an I2C API, but I would like a solution that also works with Intel and AMD graphics adaptors.
A solution exists for windows which respect XDDM driver display model. Windows 8 and 10 use WDDM.
In XDDM there is a windows O.S. supplied video port driver, and the hardware vendor supplies a miniport driver. When the miniport driver call's the video port driver's edid helper api (VideoPortDDCMonitorHelper), the miniport must supply 4 i2c function pointers as arguments.
In order to utilize these interfaces however you must be acting as the video port driver. So you have to write a video port lower filter driver which just passes along all the interfaces on from the windows supplied video port driver to the miniport driver. Hook the api's and export them to a usermode driver or ioctl which an application can call.
It may be possible to simply mount an instance of the miniport driver and some how get it to call VideoPortDDCMonitorHelper. But with out the help of the actual video port driver it would be difficult to get guidance on how to do that. Also you would have 2 instances of the driver running which may be against the rules for windows.
It does not appear this solution works for windows 8 and 10 because they use a different display driver model which doesn't appear to expose low level control of i2c. It is internal to the miniport driver.
I am new to Linux Device driver and trying to understand Linux device driver model which says a device must registered with its respected bus, be it the platform bus or real spi/i2c bus.
I could see the following macro which registered the i2c client device to its i2c bus.
module_i2c_driver(lm73_driver);
But I am not sure how it happen for a spi client device for example a CPLD/FPGA device sits on the spi bus.
Is such registrations based on the type of device?(block device or char device)