Re: [MIPI SEQ PARSING v2 PATCH 01/11] drm/i915: Adding the parsing logic for the i2c element

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 10 Sep 2015, Deepak M <m.deepak@intel.com> wrote:
> From: vkorjani <vikas.korjani@intel.com>
>
> New sequence element for i2c is been added in the
> mipi sequence block of the VBT. This patch parses
> and executes the i2c sequence.
>
> v2: Add i2c_put_adapter call(Jani), rebase
>
> Signed-off-by: vkorjani <vikas.korjani@intel.com>
> Signed-off-by: Deepak M <m.deepak@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_bios.c          |    6 +++
>  drivers/gpu/drm/i915/intel_bios.h          |    1 +
>  drivers/gpu/drm/i915/intel_dsi_panel_vbt.c |   61 ++++++++++++++++++++++++++++
>  3 files changed, 68 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index c8acc29..0bf0942 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -714,6 +714,12 @@ static u8 *goto_next_sequence(u8 *data, int *size)
>  
>  			data += 3;
>  			break;
> +		case MIPI_SEQ_ELEM_I2C:
> +			/* skip by this element payload size */
> +			data += 7;
> +			len = *data;
> +			data += len + 1;
> +			break;
>  		default:
>  			DRM_ERROR("Unknown element\n");
>  			return NULL;
> diff --git a/drivers/gpu/drm/i915/intel_bios.h b/drivers/gpu/drm/i915/intel_bios.h
> index 1b7417e..21a7f3f 100644
> --- a/drivers/gpu/drm/i915/intel_bios.h
> +++ b/drivers/gpu/drm/i915/intel_bios.h
> @@ -956,6 +956,7 @@ enum mipi_seq_element {
>  	MIPI_SEQ_ELEM_SEND_PKT,
>  	MIPI_SEQ_ELEM_DELAY,
>  	MIPI_SEQ_ELEM_GPIO,
> +	MIPI_SEQ_ELEM_I2C,
>  	MIPI_SEQ_ELEM_STATUS,

Side note, MIPI_SEQ_ELEM_STATUS doesn't seem to be in spec.


>  	MIPI_SEQ_ELEM_MAX
>  };
> diff --git a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
> index a5e99ac..9989f61 100644
> --- a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
> +++ b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
> @@ -31,6 +31,7 @@
>  #include <drm/drm_panel.h>
>  #include <linux/slab.h>
>  #include <video/mipi_display.h>
> +#include <linux/i2c.h>
>  #include <asm/intel-mid.h>
>  #include <video/mipi_display.h>
>  #include "i915_drv.h"
> @@ -104,6 +105,65 @@ static struct gpio_table gtable[] = {
>  	{ GPIO_NC_11_PCONF0, GPIO_NC_11_PAD, 0}
>  };
>  
> +static const u8 *mipi_exec_i2c(struct intel_dsi *intel_dsi, const u8 *data)
> +{
> +	struct i2c_adapter *adapter;
> +	int ret;
> +	u8 reg_offset, payload_size, retries = 5;
> +	struct i2c_msg msg;
> +	u8 *transmit_buffer = NULL;
> +	u8 flag = *data++;
> +	u8 index = *data++;
> +	u8 bus_number = *data++;
> +	u16 slave_add = *(u16 *)(data);
> +
> +	data = data + 2;
> +	reg_offset = *data++;
> +	payload_size = *data++;
> +
> +	adapter = i2c_get_adapter(bus_number);
> +
> +	if (!adapter) {
> +		DRM_ERROR("i2c_get_adapter(%u) failed, index:%u flag: %u\n",
> +				(bus_number + 1), index, flag);

Why do you log bus_number + 1 instead of what was actually tried?

I don't see why the flag/index are useful for in the message, as they're
not relevant to the i2c_get_adapter failing.

> +		goto out;
> +	}
> +
> +	transmit_buffer = kmalloc(1 + payload_size, GFP_TEMPORARY);
> +
> +	if (!transmit_buffer)
> +		goto out;
> +
> +	transmit_buffer[0] = reg_offset;
> +	memcpy(&transmit_buffer[1], data, (size_t)payload_size);

Why do you need the cast?

> +
> +	msg.addr   = slave_add;
> +	msg.flags  = 0;
> +	msg.len    = payload_size + 1;
> +	msg.buf    = &transmit_buffer[0];
> +
> +	do {
> +		ret =  i2c_transfer(adapter, &msg, 1);
> +		if (ret == 1)
> +			break;
> +		else if (ret == -EAGAIN)
> +			usleep_range(1000, 2500);
> +		else {
> +			DRM_ERROR("i2c transfer failed, error code:%d", ret);

\n missing.

> +			break;
> +		}
> +	} while (retries--);
> +
> +	if (retries == 0)

Due to the way you post-decrement retries, you may end up here even if
the transfer succeeds on the last try.

You may also end up printing two error messages, if i2c_transfer fails
on the last try.

> +		DRM_ERROR("i2c transfer failed, error code:%d", ret);

\n missing.

> +out:
> +	kfree(transmit_buffer);
> +	i2c_put_adapter(adapter);
> +
> +	data = data + payload_size;
> +	return data;
> +}
> +
>  static inline enum port intel_dsi_seq_port_to_port(u8 port)
>  {
>  	return port ? PORT_C : PORT_A;
> @@ -236,6 +296,7 @@ static const fn_mipi_elem_exec exec_elem[] = {
>  	mipi_exec_send_packet,
>  	mipi_exec_delay,
>  	mipi_exec_gpio,
> +	mipi_exec_i2c,
>  	NULL, /* status read; later */
>  };
>  
> -- 
> 1.7.9.5
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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