Messages in this thread | | | Date | Thu, 16 Nov 2023 20:07:59 +0800 | Subject | Re: [PATCH 8/8] drm/bridge: it66121: Allow link this driver as a lib | From | Sui Jingfeng <> |
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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@linux.dev> >> 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! > >
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