In the real world, graphics hardware tend to have multiple display
connectors. However, usually the connectors share one register space but
still keeping different PLL timings and display lanes.
This new class should represent a group of multiple display connectors
working together in the same Intel graphics adapter. This opens an
opportunity to abstract the interface so we could support future Intel
iGPU generations.
This is also a preparation before the driver can support newer devices
and utilize their capabilities.
The mentioned preparation is applied in a these aspects:
1. The code is splitted into more classes to adjust to future expansion.
2 classes are introduced: IntelDisplayPlane and IntelDisplayTranscoder,
so the IntelDisplayPlane controls the plane registers and second class
controls the pipeline (transcoder, encoder) registers. On gen4 it's not
really useful because there are probably one plane and one encoder to
care about, but in future generations, there are likely to be multiple
transcoders and planes to accommodate multi head support.
2. The set_edid_bytes method in the DisplayConnector class can now be
told to not assume the provided EDID bytes are always invalid. Therefore
it can refrain from printing error messages if this flag parameter is
true. This is useful for supporting real hardware situation when on boot
not all ports are connected to a monitor, which can result in floating
bus condition (essentially all the bytes we read are 0xFF).
3. An IntelNativeDisplayConnector could now be set to flag other types
of connections such as eDP (embedded DisplayPort), Analog output, etc.
This is important because on the Intel gen4 graphics we could assume to
have one analog output connector, but on future generations this is very
likely to not be the case, as there might be no VGA outputs, but rather
only an eDP connector which is converted to VGA by a design choice of
the motherboard manufacturer.
4. Add ConnectorIndex to IntelNativeDisplayConnector class - Currently
this is used to verify we always handle the correct connector when doing
modesetting.
Later, it will be used to locate special settings needed when handling
connector requests.
5. Prepare to support more types of display planes. For example, the
Intel Skylake register set for display planes is a bit different, so
let's ensure we can properly support it in the near future.
Splitting the I2C-related code lets the DisplayConnector code to utilize
I2C operations without caring about the specific details of the hardware
and allow future expansion of the driver to other newer generations
sharing the same GMBus code.
We should require a timeout for GMBus operations always, because faulty
hardware could let us just spin forever. Also, if nothing is listening
to the bus (which should result in a NAK), we could also spin forever.
Thanks to Andrew Kaster, which gave a review back in October, about a
big PR I opened (#15502), I managed to figure out why we always had a
problem with the first byte being read into the EDID buffer with the
GMBus code. It turns out that this simple invalid cast was making the
entire problem and using the correct AK::Array::data() method fixed this
notorious long standing problem for good.
Instead of using a clunky switch-case paradigm, we now have all drivers
being declaring two methods for their adapter class - create and probe.
These methods are linked in each PCIGraphicsDriverInitializer structure,
in a new s_initializers static list of them.
Then, when we probe for a PCI device, we use each probe method and if
there's a match, then the corresponding create method is called.
As a result of this change, it's much more easy to add more drivers and
the initialization code is more readable.
Many code patterns and hardware procedures rely on reliable delay in the
microseconds granularity, and since they are using such delays which are
valid cases, but should not rely on x86 specific code, we allow to
determine in compile time the proper platform-specific code to use to
invoke such delays.
Until now, our kernel has reimplemented a number of AK classes to
provide automatic internal locking:
- RefPtr
- NonnullRefPtr
- WeakPtr
- Weakable
This patch renames the Kernel classes so that they can coexist with
the original AK classes:
- RefPtr => LockRefPtr
- NonnullRefPtr => NonnullLockRefPtr
- WeakPtr => LockWeakPtr
- Weakable => LockWeakable
The goal here is to eventually get rid of the Lock* classes in favor of
using external locking.
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
The mmap interface was removed when we introduced the DisplayConnector
class, as it was quite unsafe to use and didn't handle switching between
graphical and text modes safely. By using the SharedFramebufferVMObject,
we are able to elegantly coordinate the switch by remapping the attached
mmap'ed-Memory::Region(s) with different mappings, therefore, keeping
WindowServer to think that the mappings it has are still valid, while
they are going to a different physical range until we are back to the
graphical mode (after a switch from text mode).
Most drivers take advantage of the fact that we know where is the actual
framebuffer in physical memory space, the SharedFramebufferVMObject is
created with that information. However, the VirtIO driver is different
in that aspect, because it relies on DMA transactions to show graphics
on the framebuffer, so the SharedFramebufferVMObject is created with
that mindset to support the arbitrary framebuffer location in physical
memory space.
