On 10.08.21 16:13, Muni Sekhar wrote:
On Mon, Aug 9, 2021 at 1:45 PM Oliver Neukum <oneukum@suse.com> wrote:
On 09.08.21 09:58, Muni Sekhar wrote:
Hi all,
PCIe memory mapped registers can be read via readb(), readw(), readl() kernel API's. Similarly what are the kernel API to read the device registers via USB bus
Hi,
I am afraid this is based on a fundamental misunderstanding on how USB works. It is based on passing messages, not reading and writing registers.
I am referring to the code mentioned in https://patchwork.kernel.org/project/linux-arm-msm/patch/1534464348-8227-3-g...
As per this driver gets access to the Qcomm’s USB h/w device registers via devm_extcon_dev_allocate(), devm_extcon_dev_register(), platform_get_resource() and devm_ioremap_resource API’s.
What does the USB external connector EXTCON_USB \ EXTCON_USB_HOST devices means? Are these different from normal USB devices?
Hi, those are not USB devices. Those are devices associated with a USB bus and are to be found on the host's CPU's bus. This is like a graphics card is from the driver's view not a DisplayPort device or a SCSI controller is not a SCSI device for its driver. A host controller and associated devices can be on any bus. Such controllers follow their separate specifications and how they are to be driven is strictly speaking not part of USB: Regards Oliver