On 2014년 08월 18일 20:38, Andrzej Hajda wrote:
> On 08/18/2014 10:11 AM, Inki Dae wrote:
>> This patch adds a new flag, MIPI_DSI-MODE_LPM, to transmit data
>> in low power. With this flag, msg.flags has MIPI_DSI_MSG_USE_LPM
>> so that host driver of each SoC can clear or set relevant register
>> bit for low power transmission.
>>
>> All host drivers shall support continuous clock behavior on the
>> Clock Lane, and optionally may support non-continuous clock behavior.
>> Both of them can transmit data in high speed of low power.
>>
>> With each clock behavior, non-continuous or continuous clock mode,
>> host controller will transmit data in high speed by default so if
>> peripheral wants to receive data in low power, the peripheral driver
>> should set MIPI_DSI_MODE_LPM flag.
>
> I think it would be better to remove last two paragraphs as irrelevant,
> LPM and clock behavior are orthogonal.
>
>>
>> Signed-off-by: Inki Dae <inki.dae@xxxxxxxxxxx>
>> ---
>> drivers/gpu/drm/drm_mipi_dsi.c | 6 ++++++
>> include/drm/drm_mipi_dsi.h | 2 ++
>> 2 files changed, 8 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
>> index 6aa6a9e..eb6dfe5 100644
>> --- a/drivers/gpu/drm/drm_mipi_dsi.c
>> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
>> @@ -231,6 +231,9 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
>> break;
>> }
>>
>> + if (dsi->mode_flags & MIPI_DSI_MODE_LPM)
>> + msg.flags = MIPI_DSI_MSG_USE_LPM;
>> +
>> return ops->transfer(dsi->host, &msg);
>> }
>> EXPORT_SYMBOL(mipi_dsi_dcs_write);
>> @@ -260,6 +263,9 @@ ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
>> if (!ops || !ops->transfer)
>> return -ENOSYS;
>>
>> + if (dsi->mode_flags & MIPI_DSI_MODE_LPM)
>> + msg.flags = MIPI_DSI_MSG_USE_LPM;
>> +
>
> I see three other ways of adding LPM to DCS:
>
> 1. Add flags argument to DCS command, eg:
> mipi_dsi_dcs_write(dsi, data, len, flags)
>
> 2. Pass struct mipi_dsi_device to transfer callback:
> ssize_t (*transfer)(struct mipi_dsi_device *dsi,
> struct mipi_dsi_msg *msg);
> or
> ssize_t (*transfer)(struct mipi_dsi_host *host,
> struct mipi_dsi_device *dsi,
> struct mipi_dsi_msg *msg);
>
> This way DSI host will have access to mipi_dsi_device
> and to its flags.
>
> 3. Create new API function, lets call it dsi_transfer, which
> should by called by DCS helpers instead of transfer op.
> This function shall translate device flags to message flags
> and call the original op.
>
> I think the 3rd solution is the best one, but I have no strong feelings
> against the other ones, including your.
> As I remember Thierry have also some ideas about changes in DSI API
> so I have added him to CC.
Thanks for comments and CCing Thierry.
I think it'd better to handle this solution flexibly. There was a
concern that my solution makes all commands to be transmitted in low
power or high speed by default. So if we have other solution which
passes a flag per a message, then we could transmit each command in low
power or high speed, which could also be used selectively with my
solution - if msg->flags has MIPI_DSI_MODE_LPM, then each flag of the
new API is ignored.
Thierry, which one do you prefer? Otherwise, do you have other opinions?
Thanks,
Inki Dae
>
> Regards
> Andrzej
>
>
>> return ops->transfer(dsi->host, &msg);
>> }
>> EXPORT_SYMBOL(mipi_dsi_dcs_read);
>> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
>> index 2bb55b8..8569dc5 100644
>> --- a/include/drm/drm_mipi_dsi.h
>> +++ b/include/drm/drm_mipi_dsi.h
>> @@ -96,6 +96,8 @@ void mipi_dsi_host_unregister(struct mipi_dsi_host *host);
>> #define MIPI_DSI_MODE_EOT_PACKET BIT(9)
>> /* device supports non-continuous clock behavior (DSI spec 5.6.1) */
>> #define MIPI_DSI_CLOCK_NON_CONTINUOUS BIT(10)
>> +/* transmit data in low power */
>> +#define MIPI_DSI_MODE_LPM BIT(11)
>>
>> enum mipi_dsi_pixel_format {
>> MIPI_DSI_FMT_RGB888,
>
>
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