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| author | Rob Herring (Arm) <robh@kernel.org> | 2026-08-31 14:43:51 -0500 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2026-09-13 18:17:31 -0700 |
| commit | 55fc280e951ab2b39f3dcb640edc1b1eebc6d173 (patch) | |
| tree | f0b5f37b42fc13b9908a31b657c646b024231cdd /Documentation/driver-api/sm501.rst | |
| download | linux-stable-55fc280e951ab2b39f3dcb640edc1b1eebc6d173.tar.gz linux-stable-55fc280e951ab2b39f3dcb640edc1b1eebc6d173.zip | |
Input: tsc2007 - read "ti,poll-period" as u32grafted
The "ti,poll-period" property is documented as a normal uint32 cell.
The driver used a u64 helper, which makes the helper type disagree with
the schema even though the stored value is still small.
Read "ti,poll-period" with the u32 helper matching the documented DT
cell size.
Assisted-by: Codex:gpt-5-5
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260831194352.1185860-1-robh@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'Documentation/driver-api/sm501.rst')
| -rw-r--r-- | Documentation/driver-api/sm501.rst | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/Documentation/driver-api/sm501.rst b/Documentation/driver-api/sm501.rst new file mode 100644 index 000000000..882507453 --- /dev/null +++ b/Documentation/driver-api/sm501.rst @@ -0,0 +1,74 @@ +.. include:: <isonum.txt> + +============ +SM501 Driver +============ + +:Copyright: |copy| 2006, 2007 Simtec Electronics + +The Silicon Motion SM501 multimedia companion chip is a multifunction device +which may provide numerous interfaces including USB host controller USB gadget, +asynchronous serial ports, audio functions, and a dual display video interface. +The device may be connected by PCI or local bus with varying functions enabled. + +Core +---- + +The core driver in drivers/mfd provides common services for the +drivers which manage the specific hardware blocks. These services +include locking for common registers, clock control and resource +management. + +The core registers drivers for both PCI and generic bus based +chips via the platform device and driver system. + +On detection of a device, the core initialises the chip (which may +be specified by the platform data) and then exports the selected +peripheral set as platform devices for the specific drivers. + +The core re-uses the platform device system as the platform device +system provides enough features to support the drivers without the +need to create a new bus-type and the associated code to go with it. + + +Resources +--------- + +Each peripheral has a view of the device which is implicitly narrowed to +the specific set of resources that peripheral requires in order to +function correctly. + +The centralised memory allocation allows the driver to ensure that the +maximum possible resource allocation can be made to the video subsystem +as this is by-far the most resource-sensitive of the on-chip functions. + +The primary issue with memory allocation is that of moving the video +buffers once a display mode is chosen. Indeed when a video mode change +occurs the memory footprint of the video subsystem changes. + +Since video memory is difficult to move without changing the display +(unless sufficient contiguous memory can be provided for the old and new +modes simultaneously) the video driver fully utilises the memory area +given to it by aligning fb0 to the start of the area and fb1 to the end +of it. Any memory left over in the middle is used for the acceleration +functions, which are transient and thus their location is less critical +as it can be moved. + + +Configuration +------------- + +The platform device driver uses a set of platform data to pass +configurations through to the core and the subsidiary drivers +so that there can be support for more than one system carrying +an SM501 built into a single kernel image. + +The PCI driver assumes that the PCI card behaves as per the Silicon +Motion reference design. + +There is an errata (AB-5) affecting the selection of the +of the M1XCLK and M1CLK frequencies. These two clocks +must be sourced from the same PLL, although they can then +be divided down individually. If this is not set, then SM501 may +lock and hang the whole system. The driver will refuse to +attach if the PLL selection is different. |
