linux-kernel - Re: [PATCH RFC 1/7] drm/mipi-dsi: wrap more functions for streamline handling

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Date: Sat, 11 May 2024 01:22:58 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Doug Anderson <dianders@...omium.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Sam Ravnborg <sam@...nborg.org>, Sumit Semwal <sumit.semwal@...aro.org>, 
	Caleb Connolly <caleb.connolly@...aro.org>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	Vinod Koul <vkoul@...nel.org>, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 1/7] drm/mipi-dsi: wrap more functions for streamline
 handling

On Fri, May 10, 2024 at 02:45:45PM -0700, Doug Anderson wrote:
> Hi,
> 
> On Thu, May 9, 2024 at 3:37 PM Dmitry Baryshkov
> <dmitry.baryshkov@...aro.org> wrote:
> >
> > +/**
> > + * mipi_dsi_compression_mode_ext() - enable/disable DSC on the peripheral
> > + * @ctx: Context for multiple DSI transactions
> > + * @enable: Whether to enable or disable the DSC
> > + * @algo: Selected compression algorithm
> > + * @pps_selector: Select PPS from the table of pre-stored or uploaded PPS entries
> > + *
> > + * Like mipi_dsi_compression_mode_ext_multi() but deals with errors in a way that
> > + * makes it convenient to make several calls in a row.
> 
> Your comment is backward. The name of the function is

True, my bad.

> mipi_dsi_compression_mode_ext_multi() not
> mipi_dsi_compression_mode_ext(). ...and it's like
> mipi_dsi_compression_mode_ext() not like
> mipi_dsi_compression_mode_ext_multi().
> 
> 
> > @@ -338,6 +345,18 @@ int mipi_dsi_dcs_set_display_brightness_large(struct mipi_dsi_device *dsi,
> >  int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,
> >                                              u16 *brightness);
> >
> > +void mipi_dsi_dcs_nop_multi(struct mipi_dsi_multi_context *ctx);
> > +void mipi_dsi_dcs_enter_sleep_mode_multi(struct mipi_dsi_multi_context *ctx);
> > +void mipi_dsi_dcs_exit_sleep_mode_multi(struct mipi_dsi_multi_context *ctx);
> > +void mipi_dsi_dcs_set_display_off_multi(struct mipi_dsi_multi_context *ctx);
> > +void mipi_dsi_dcs_set_display_on_multi(struct mipi_dsi_multi_context *ctx);
> > +void mipi_dsi_dcs_set_tear_on_multi(struct mipi_dsi_multi_context *ctx,
> > +                                   enum mipi_dsi_dcs_tear_mode mode);
> > +
> > +#define mipi_dsi_msleep(ctx, delay)    \
> > +       if (!ctx.accum_err)             \
> > +               msleep(delay)           \
> 
> Please enclose the above in a "do { ... } while (0)" as typical for
> macros. Otherwise you could possibly get some very surprising
> behavior:

Ack.

> 
> if (needs_big_delay)
>   mipi_dsi_msleep(ctx, 50)
> else
>   mipi_dsi_msleep(ctx, 10)
> 
> ...with your macro as it is I think the "else" will match up against
> the "if !(ctx.accum_err)" inside the macro and not against the "if
> (needs_big_delay)"
> 
> Also: nit that the mipi_dsi_msleep() should probably be defined above
> the "mipi_dsi_dcs" section.
> 
> 
> -Doug

-- 
With best wishes
Dmitry