[PATCH v4 65/80] drm/omap: dsi: skip dsi_vc_enable_hs when already in correct mode

[Laurent Pinchart]

Hi Tomi,

Thank you for the patch.

On Tue, Nov 24, 2020 at 02:45:23PM +0200, Tomi Valkeinen wrote:
> Simplify and optimize dsi_vc_enable_hs() so that it can be called
> without checking the current HS/LP mode. Make dsi_vc_enable_hs() return
> if the VC is already in the correct mode.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
> ---
>  drivers/gpu/drm/omapdrm/dss/dsi.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> index 4ac82166edc3..c3f13226ac26 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> @@ -341,7 +341,6 @@ struct dsi_data {
>  	int irq;
>  
>  	bool is_enabled;
> -	bool in_lp_mode;
>  
>  	struct clk *dss_clk;
>  	struct regmap *syscon;
> @@ -2441,6 +2440,9 @@ static void dsi_vc_enable_hs(struct omap_dss_device *dssdev, int vc,
>  
>  	DSSDBG("dsi_vc_enable_hs(%d, %d)\n", vc, enable);
>  
> +	if (REG_GET(dsi, DSI_VC_CTRL(vc), 9, 9) == enable)
> +		return;
> +

I tend to prefer cached state instead of reading it back from the
hardware, as it's (marginally) more efficient. In either case,

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  	WARN_ON(!dsi_bus_is_locked(dsi));
>  
>  	dsi_vc_enable(dsi, vc, 0);
> @@ -2456,8 +2458,6 @@ static void dsi_vc_enable_hs(struct omap_dss_device *dssdev, int vc,
>  	/* start the DDR clock by sending a NULL packet */
>  	if (dsi->vm_timings.ddr_clk_always_on && enable)
>  		dsi_vc_send_null(dsi, vc, dsi->dsidev->channel);
> -
> -	dsi->in_lp_mode = !enable;
>  }
>  
>  static void dsi_vc_flush_long_data(struct dsi_data *dsi, int vc)
> @@ -4886,9 +4886,7 @@ static ssize_t _omap_dsi_host_transfer(struct dsi_data *dsi, int vc,
>  	struct omap_dss_device *dssdev = &dsi->output;
>  	int r;
>  
> -	if (!!(msg->flags & MIPI_DSI_MSG_USE_LPM) != dsi->in_lp_mode)
> -		dsi_vc_enable_hs(dssdev, vc,
> -				 !(msg->flags & MIPI_DSI_MSG_USE_LPM));
> +	dsi_vc_enable_hs(dssdev, vc, !(msg->flags & MIPI_DSI_MSG_USE_LPM));
>  
>  	switch (msg->type) {
>  	case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:

-- 
Regards,

Laurent Pinchart