On Mon, Oct 08, 2012 at 02:13:50PM +0200, Laurent Pinchart wrote:
> Hi Steffen,
>
> Thanks for the patch.
>
> On Thursday 04 October 2012 19:59:20 Steffen Trumtrar wrote:
> > Get videomode from devicetree in a format appropriate for the
> > backend. drm_display_mode and fb_videomode are supported atm.
> > Uses the display signal timings from of_display_timings
> >
> > Signed-off-by: Steffen Trumtrar <s.trumt...@pengutronix.de>
> > ---
> > drivers/of/Kconfig | 5 +
> > drivers/of/Makefile | 1 +
> > drivers/of/of_videomode.c | 212 +++++++++++++++++++++++++++++++++++++++
> > include/linux/of_videomode.h | 41 ++++++++
> > 4 files changed, 259 insertions(+)
> > create mode 100644 drivers/of/of_videomode.c
> > create mode 100644 include/linux/of_videomode.h
> >
> > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> > index 646deb0..74282e2 100644
> > --- a/drivers/of/Kconfig
> > +++ b/drivers/of/Kconfig
> > @@ -88,4 +88,9 @@ config OF_DISPLAY_TIMINGS
> > help
> > helper to parse display timings from the devicetree
> >
> > +config OF_VIDEOMODE
> > + def_bool y
> > + help
> > + helper to get videomodes from the devicetree
> > +
> > endmenu # OF
> > diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> > index c8e9603..09d556f 100644
> > --- a/drivers/of/Makefile
> > +++ b/drivers/of/Makefile
> > @@ -12,3 +12,4 @@ obj-$(CONFIG_OF_PCI) += of_pci.o
> > obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o
> > obj-$(CONFIG_OF_MTD) += of_mtd.o
> > obj-$(CONFIG_OF_DISPLAY_TIMINGS) += of_display_timings.o
> > +obj-$(CONFIG_OF_VIDEOMODE) += of_videomode.o
> > diff --git a/drivers/of/of_videomode.c b/drivers/of/of_videomode.c
> > new file mode 100644
> > index 0000000..76ac16e
> > --- /dev/null
> > +++ b/drivers/of/of_videomode.c
> > @@ -0,0 +1,212 @@
> > +/*
> > + * generic videomode helper
> > + *
> > + * Copyright (c) 2012 Steffen Trumtrar <s.trumt...@pengutronix.de>,
> > Pengutronix
> > + *
> > + * This file is released under the GPLv2
> > + */
> > +#include <linux/of.h>
> > +#include <linux/fb.h>
> > +#include <linux/slab.h>
> > +#include <drm/drm_mode.h>
> > +#include <linux/of_display_timings.h>
> > +#include <linux/of_videomode.h>
> > +
> > +void dump_fb_videomode(struct fb_videomode *m)
> > +{
> > + pr_debug("fb_videomode = %d %d %d %d %d %d %d %d %d %d %d %d %d\n",
>
> That's going to be pretty difficult to read :-) Would it make sense to group
> several attributes logically (for instance using %ux%u for m->xres, m->yres) ?
>
No problem. That can be changed.
> > + m->refresh, m->xres, m->yres, m->pixclock, m->left_margin,
> > + m->right_margin, m->upper_margin, m->lower_margin, +
> > m->hsync_len, m->vsync_len, m->sync, m->vmode, m->flag);
> > +}
>
> Shouldn't this (and the other non exported functions below) be static ?
>
Yes.
> > +void dump_drm_displaymode(struct drm_display_mode *m)
> > +{
> > + pr_debug("drm_displaymode = %d %d %d %d %d %d %d %d %d\n",
> > + m->hdisplay, m->hsync_start, m->hsync_end, m->htotal,
> > + m->vdisplay, m->vsync_start, m->vsync_end, m->vtotal,
> > + m->clock);
> > +}
> > +
> > +int videomode_from_timing(struct display_timings *disp, struct videomode
> > *vm,
> > + int index)
> > +{
> > + struct signal_timing *st = NULL;
> > +
> > + if (!vm)
> > + return -EINVAL;
> > +
>
> What about making vm a mandatory argument ? It looks to me like a caller bug
> if vm is NULL.
>
The caller must provide the struct videomode, yes. Wouldn't the kernel hang
itself
with a NULL pointer exception, if I just work with it ?
> > + st = display_timings_get(disp, index);
> > +
>
> You can remove the blank line.
>
> > + if (!st) {
> > + pr_err("%s: no signal timings found\n", __func__);
> > + return -EINVAL;
> > + }
> > +
> > + vm->pixelclock = signal_timing_get_value(&st->pixelclock, 0);
> > + vm->hactive = signal_timing_get_value(&st->hactive, 0);
> > + vm->hfront_porch = signal_timing_get_value(&st->hfront_porch, 0);
> > + vm->hback_porch = signal_timing_get_value(&st->hback_porch, 0);
> > + vm->hsync_len = signal_timing_get_value(&st->hsync_len, 0);
> > +
> > + vm->vactive = signal_timing_get_value(&st->vactive, 0);
> > + vm->vfront_porch = signal_timing_get_value(&st->vfront_porch, 0);
> > + vm->vback_porch = signal_timing_get_value(&st->vback_porch, 0);
> > + vm->vsync_len = signal_timing_get_value(&st->vsync_len, 0);
> > +
> > + vm->vah = st->vsync_pol_active_high;
> > + vm->hah = st->hsync_pol_active_high;
> > + vm->interlaced = st->interlaced;
> > + vm->doublescan = st->doublescan;
> > +
> > + return 0;
> > +}
> > +
> > +int of_get_videomode(struct device_node *np, struct videomode *vm, int
> > index)
>
> I wonder how to avoid abuse of this functions. It's a useful helper for
> drivers that need to get a video mode once only, but would result in lower
> performances if a driver calls it for every mode. Drivers must call
> of_get_display_timing_list instead in that case and case the display timings.
> I'm wondering whether we should really expose of_get_videomode.
>
The intent was to let the driver decide. That way all the other overhead may
be skipped.
> > +{
> > + struct display_timings *disp;
> > + int ret = 0;
>
> No need to assign ret to 0 here.
>
Ah, yes. Unneeded in this case.
> > +
> > + disp = of_get_display_timing_list(np);
> > +
>
> You can remove the blank line.
>
> > + if (!disp) {
> > + pr_err("%s: no timings specified\n", __func__);
> > + return -EINVAL;
> > + }
> > +
> > + if (index == OF_DEFAULT_TIMING)
> > + index = disp->default_timing;
> > +
> > + ret = videomode_from_timing(disp, vm, index);
> > +
>
> No need for a blank line.
>
> > + if (ret)
> > + return ret;
> > +
> > + display_timings_release(disp);
> > +
> > + if (!vm) {
> > + pr_err("%s: could not get videomode %d\n", __func__, index);
> > + return -EINVAL;
> > + }
>
> This can't happen. If vm is NULL the videomode_from_timing call above will
> return -EINVAL, and this function will then return immediately without
> reaching this code block.
>
Okay.
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(of_get_videomode);
> > +
> > +#if defined(CONFIG_DRM)
> > +int videomode_to_display_mode(struct videomode *vm, struct drm_display_mode
> > *dmode)
> > +{
> > + memset(dmode, 0, sizeof(*dmode));
> > +
> > + dmode->hdisplay = vm->hactive;
> > + dmode->hsync_start = dmode->hdisplay + vm->hfront_porch;
> > + dmode->hsync_end = dmode->hsync_start + vm->hsync_len;
> > + dmode->htotal = dmode->hsync_end + vm->hback_porch;
> > +
> > + dmode->vdisplay = vm->vactive;
> > + dmode->vsync_start = dmode->vdisplay + vm->vfront_porch;
> > + dmode->vsync_end = dmode->vsync_start + vm->vsync_len;
> > + dmode->vtotal = dmode->vsync_end + vm->vback_porch;
> > +
> > + dmode->clock = vm->pixelclock / 1000;
> > +
> > + if (vm->hah)
> > + dmode->flags |= DRM_MODE_FLAG_PHSYNC;
> > + else
> > + dmode->flags |= DRM_MODE_FLAG_NHSYNC;
> > + if (vm->vah)
> > + dmode->flags |= DRM_MODE_FLAG_PVSYNC;
> > + else
> > + dmode->flags |= DRM_MODE_FLAG_NVSYNC;
> > + if (vm->interlaced)
> > + dmode->flags |= DRM_MODE_FLAG_INTERLACE;
> > + if (vm->doublescan)
> > + dmode->flags |= DRM_MODE_FLAG_DBLSCAN;
> > + drm_mode_set_name(dmode);
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(videomode_to_display_mode);
> > +
> > +int of_get_drm_display_mode(struct device_node *np, struct drm_display_mode
> > *dmode,
> > + int index)
>
> Same as above, do we really need to expose this helper function ? If so we
> should at least clearly document (using kerneldoc for instance) that drivers
> should only use it if they need to get a single mode once.
>
> > +{
> > + struct videomode vm;
> > + int ret;
> > +
> > + ret = of_get_videomode(np, &vm, index);
> > +
> > + if (ret)
> > + return ret;
> > +
> > + videomode_to_display_mode(&vm, dmode);
> > +
> > + pr_info("%s: got %dx%d display mode from %s\n", __func__, vm.hactive,
> > + vm.vactive, np->name);
> > + dump_drm_displaymode(dmode);
> > +
> > + return 0;
> > +
> > +}
> > +EXPORT_SYMBOL_GPL(of_get_drm_display_mode);
> > +#else
> > +int videomode_to_display_mode(struct videomode *vm, struct drm_display_mode
> > *dmode)
> > +{
> > + return 0;
> > +}
> > +
> > +int of_get_drm_display_mode(struct device_node *np, struct drm_display_mode
> > *dmode,
> > + int index)
> > +{
> > + return 0;
> > +}
>
> What about not defining those if CONFIG_DRM is not set ? No driver should
> call
> these functions in that case. If we really need those stubs they should
> return
> an error.
>
Okay. I will remove them.
> > +#endif
> > +
> > +int videomode_to_fb_videomode(struct videomode *vm, struct fb_videomode
> > *fbmode)
> > +{
> > + memset(fbmode, 0, sizeof(*fbmode));
> > +
> > + fbmode->xres = vm->hactive;
> > + fbmode->left_margin = vm->hback_porch;
> > + fbmode->right_margin = vm->hfront_porch;
> > + fbmode->hsync_len = vm->hsync_len;
> > +
> > + fbmode->yres = vm->vactive;
> > + fbmode->upper_margin = vm->vback_porch;
> > + fbmode->lower_margin = vm->vfront_porch;
> > + fbmode->vsync_len = vm->vsync_len;
> > +
> > + fbmode->pixclock = KHZ2PICOS(vm->pixelclock) / 1000;
> > +
> > + if (vm->hah)
> > + fbmode->sync |= FB_SYNC_HOR_HIGH_ACT;
> > + if (vm->vah)
> > + fbmode->sync |= FB_SYNC_VERT_HIGH_ACT;
> > + if (vm->interlaced)
> > + fbmode->vmode |= FB_VMODE_INTERLACED;
> > + if (vm->doublescan)
> > + fbmode->vmode |= FB_VMODE_DOUBLE;
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(videomode_to_fb_videomode);
> > +
> > +int of_get_fb_videomode(struct device_node *np, struct fb_videomode *fb,
> > + int index)
> > +{
> > + struct videomode vm;
> > + int ret;
> > +
> > + ret = of_get_videomode(np, &vm, index);
> > + if (ret)
> > + return ret;
> > +
> > + videomode_to_fb_videomode(&vm, fb);
> > +
> > + pr_info("%s: got %dx%d display mode from %s\n", __func__, vm.hactive,
> > + vm.vactive, np->name);
> > + dump_fb_videomode(fb);
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(of_get_drm_display_mode);
> > diff --git a/include/linux/of_videomode.h b/include/linux/of_videomode.h
> > new file mode 100644
> > index 0000000..96efe01
> > --- /dev/null
> > +++ b/include/linux/of_videomode.h
> > @@ -0,0 +1,41 @@
> > +/*
> > + * Copyright 2012 Steffen Trumtrar <s.trumt...@pengutronix.de>
> > + *
> > + * generic videomode description
> > + *
> > + * This file is released under the GPLv2
> > + */
> > +
> > +#ifndef __LINUX_VIDEOMODE_H
> > +#define __LINUX_VIDEOMODE_H
> > +
> > +#include <drm/drmP.h>
> > +
> > +struct videomode {
> > + u32 pixelclock;
> > + u32 refreshrate;
> > +
> > + u32 hactive;
> > + u32 hfront_porch;
> > + u32 hback_porch;
> > + u32 hsync_len;
> > +
> > + u32 vactive;
> > + u32 vfront_porch;
> > + u32 vback_porch;
> > + u32 vsync_len;
> > +
> > + bool hah;
> > + bool vah;
> > + bool interlaced;
> > + bool doublescan;
> > +
> > +};
> > +
> > +int videomode_to_display_mode(struct videomode *vm, struct drm_display_mode
> > *dmode); +int videomode_to_fb_videomode(struct videomode *vm, struct
> > fb_videomode *fbmode); +int of_get_videomode(struct device_node *np, struct
> > videomode *vm, int index); +int of_get_drm_display_mode(struct device_node
> > *np, struct drm_display_mode *dmode, + int index);
> > +int of_get_fb_videomode(struct device_node *np, struct fb_videomode *fb,
> > int index); +#endif /* __LINUX_VIDEOMODE_H */
> --
> Regards,
>
> Laurent Pinchart
>
Regards,
Steffen
--
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