Re: [PATCH 8/8] drm/bridge: it66121: Allow link this driver as a lib
From: Sui Jingfeng
Date: Thu Nov 16 2023 - 07:08:20 EST
On 2023/11/16 19:53, Sui Jingfeng wrote:
Hi,
On 2023/11/16 19:29, Dmitry Baryshkov wrote:
On Thu, 16 Nov 2023 at 13:18, Sui Jingfeng <sui.jingfeng@xxxxxxxxx>
wrote:
Hi,
On 2023/11/15 00:30, Dmitry Baryshkov wrote:
+
+ ctx->connector = connector;
+ }
if (ctx->info->id == ID_IT66121) {
ret = regmap_write_bits(ctx->regmap,
IT66121_CLK_BANK_REG,
@@ -1632,16 +1651,13 @@ static const char * const
it66121_supplies[] = {
"vcn33", "vcn18", "vrf12"
};
-static int it66121_probe(struct i2c_client *client)
+int it66121_create_bridge(struct i2c_client *client, bool
of_support,
+ bool hpd_support, bool audio_support,
+ struct drm_bridge **bridge)
{
+ struct device *dev = &client->dev;
int ret;
struct it66121_ctx *ctx;
- struct device *dev = &client->dev;
-
- if (!i2c_check_functionality(client->adapter,
I2C_FUNC_I2C)) {
- dev_err(dev, "I2C check functionality failed.\n");
- return -ENXIO;
- }
ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
if (!ctx)
@@ -1649,24 +1665,19 @@ static int it66121_probe(struct i2c_client
*client)
ctx->dev = dev;
ctx->client = client;
- ctx->info = i2c_get_match_data(client);
-
- ret = it66121_of_read_bus_width(dev, &ctx->bus_width);
- if (ret)
- return ret;
-
- ret = it66121_of_get_next_bridge(dev, &ctx->next_bridge);
- if (ret)
- return ret;
-
- i2c_set_clientdata(client, ctx);
mutex_init(&ctx->lock);
- ret = devm_regulator_bulk_get_enable(dev,
ARRAY_SIZE(it66121_supplies),
- it66121_supplies);
- if (ret) {
- dev_err(dev, "Failed to enable power supplies\n");
- return ret;
+ if (of_support) {
+ ret = it66121_of_read_bus_width(dev,
&ctx->bus_width);
+ if (ret)
+ return ret;
+
+ ret = it66121_of_get_next_bridge(dev,
&ctx->next_bridge);
+ if (ret)
+ return ret;
+ } else {
+ ctx->bus_width = 24;
+ ctx->next_bridge = NULL;
}
A better alternative would be to turn OF calls into fwnode calls and
to populate the fwnode properties. See
drivers/platform/x86/intel/chtwc_int33fe.c for example.
Honestly, I don't want to leave any scratch(breadcrumbs).
I'm worries about that turn OF calls into fwnode calls will leave
something unwanted.
Because I am not sure if fwnode calls will make sense in the DT
world, while my patch
*still* be useful in the DT world.
fwnode calls work for both DT and non-DT cases. In the DT case they
work with DT nodes and properties. In the non-DT case, they work with
manually populated properties.
Because the newly introduced it66121_create_bridge()
function is a core. I think It's better leave this task to a more
advance programmer.
if there have use case. It can be introduced at a latter time,
probably parallel with
the DT.
I think DT and/or ACPI is best for integrated devices, but it66121
display bridges is
a i2c slave device. Personally, I think slave device shouldn't be
standalone. I'm more
prefer to turn this driver to support hot-plug, even remove the
device on the run time
freely when detach and allow reattach. Like the I2C EEPROM device in
the monitor (which
contains the EDID, with I2C slave address 0x50). The I2C EEPROM
device *also* don't has
a corresponding struct device representation in linux kernel.
It has. See i2c_client::dev.
No, what I mean is that there don't have a device driver for
monitor(display) hardware entity.
And the drm_do_probe_ddc_edid() is the static linked driver, which is
similar with the idea
this series want to express.
so I still think It is best to make this drivers functional as a
static lib, but I want
to hear you to say more. Why it would be a *better* alternative to
turn OF calls into
fwnode calls? what are the potential benefits?
Because then you can populate device properties from your root device.
Because it allows the platform to specify the bus width instead of
hardcoding 24 bits (which might work in your case, but might not be
applicable to another user next week).
No, this problem can be easily solved. Simply add another argument.
```
int it66121_create_bridge(struct i2c_client *client, bool of_support,
bool hpd_support, bool audio_support, u32
bus_width,
struct drm_bridge **bridge);
```
Anyway, even without fwnode, I'd strongly suggest you to drop the
it66121_create_bridge() as it is now and start by populating the i2c
bus from your root device.
This will force all non-DT users to add the similar code patter at the
display controller side,
which is another kind of duplication. The monitor is also as I2C slave
device, can be abstract
as a identify drm bridges in theory, I guess.
'identify' -> 'identity'
Then you will need some way (fwnode?) to
discover the bridge chain. And at the last point you will get into the
device data and/or properties business.
No, leave that chance to a more better programmer and forgive me please,
too difficult, I'm afraid of not able to solve. Thanks a lot for the
trust!