Re: [PATCH v8 1/4] drm/bridge: add support for sn65dsi86 bridge driver

[spanda-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org]

On 2018-06-12 05:05, Stephen Boyd wrote:
> Quoting Sandeep Panda (2018-06-04 22:40:15)
>> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c 
>> b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
>> new file mode 100644
>> index 0000000..add6e0f
>> --- /dev/null
>> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
>> @@ -0,0 +1,666 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
>> + */
>> +
> [...]
>> +
>> +static const struct regmap_config ti_sn_bridge_regmap_config = {
>> +       .reg_bits = 8,
>> +       .val_bits = 8,
>> +       .volatile_table = &ti_sn_bridge_volatile_table,
>> +       .cache_type = REGCACHE_NONE,
>> +};
>> +
>> +static void ti_sn_bridge_write_u16(struct ti_sn_bridge *pdata,
>> +                                  unsigned int reg, u16 val)
>> +{
>> +       regmap_write(pdata->regmap, reg, val & 0xFF);
>> +       regmap_write(pdata->regmap, reg + 1, val >> 8);
>> +}
>> +
>> +static int __maybe_unused ti_sn_bridge_resume(struct device *dev)
>> +{
>> +       struct ti_sn_bridge *pdata = dev_get_drvdata(dev);
>> +       int ret = 0;
> 
> Please don't assign variables and then reassign them again immediately
> after. It hides use before real initialization bugs.
> 
Ok.

>> +
>> +       ret = regulator_bulk_enable(SN_REGULATOR_SUPPLY_NUM, 
>> pdata->supplies);
> [...]
>> +
>> +static int ti_sn_bridge_probe(struct i2c_client *client,
>> +        const struct i2c_device_id *id)
>> +{
>> +       struct ti_sn_bridge *pdata;
>> +       struct device_node *ddc_node;
>> +       struct mipi_dsi_host *host;
>> +       struct mipi_dsi_device *dsi;
>> +       int ret = 0;
>> +       const struct mipi_dsi_device_info info = { .type = 
>> "ti_sn_bridge",
>> +                                                  .channel = 0,
>> +                                                  .node = NULL,
>> +                                                };
>> +
>> +       if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
>> +               DRM_ERROR("device doesn't support I2C\n");
>> +               return -ENODEV;
>> +       }
>> +
>> +       ret = ti_sn_bridge_parse_dsi_host(pdata);
>> +       if (ret)
>> +               return ret;
>> +
>> +       host = of_find_mipi_dsi_host_by_node(pdata->host_node);
>> +       if (!host) {
>> +               DRM_ERROR("failed to find dsi host\n");
> 
> Not sure we want to print an error and then return -EPROBE_DEFER.
> Usually EPROBE_DEFER is silent.
> 
>> +               ret = -EPROBE_DEFER;
>> +               goto err_dsi_host;
>> +       }
>> +
> [...]
>> +
>> +       /* TODO: setting to 4 lanes always for now */
>> +       dsi->lanes = 4;
>> +       dsi->format = MIPI_DSI_FMT_RGB888;
>> +       dsi->mode_flags = MIPI_DSI_MODE_VIDEO | 
>> MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
>> +                         MIPI_DSI_MODE_EOT_PACKET | 
>> MIPI_DSI_MODE_VIDEO_HSE;
>> +
>> +       ret = mipi_dsi_attach(dsi);
>> +       if (ret < 0) {
>> +               DRM_ERROR("failed to attach dsi to host\n");
>> +               goto err_dsi_attach;
>> +       }
>> +       pdata->dsi = dsi;
>> +
>> +       pdata->refclk = devm_clk_get(pdata->dev, "refclk");
> 
> We need to check for error
> 
> 	if (IS_ERR(pdata->refclk))
> 
> And then if it's EPROBE_DEFER I suppose we would bail out, otherwise
> assume it's not present?

Yes found this issue while testing the driver on actual sn65dsi86 HW, i 
will fix this in next patchset.
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