[PATCH v5 04/10] drm/stm: Add STM32 LTDC driver

Benjamin Gaignard
2017-04-12T18:58:56Z

2017-04-11 22:45 GMT+02:00 Eric Anholt <eric@anholt.net>:
> Yannick Fertre <yannick.fertre@st.com> writes:
>
>> This controller provides output signals to interface directly a variety
>> of LCD and TFT panels. These output signals are: RGB signals
>> (up to 24bpp), vertical & horizontal synchronisations, data enable and
>> the pixel clock.
>>
>> Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
>> ---
>> drivers/gpu/drm/Kconfig | 3 +-
>> drivers/gpu/drm/Makefile | 1 +
>> drivers/gpu/drm/stm/Kconfig | 16 +
>> drivers/gpu/drm/stm/Makefile | 7 +
>> drivers/gpu/drm/stm/drv.c | 221 ++++++++
>> drivers/gpu/drm/stm/ltdc.c | 1210 ++++++++++++++++++++++++++++++++++++++++++
>> drivers/gpu/drm/stm/ltdc.h | 40 ++
>> 7 files changed, 1497 insertions(+), 1 deletion(-)
>> create mode 100644 drivers/gpu/drm/stm/Kconfig
>> create mode 100644 drivers/gpu/drm/stm/Makefile
>> create mode 100644 drivers/gpu/drm/stm/drv.c
>> create mode 100644 drivers/gpu/drm/stm/ltdc.c
>> create mode 100644 drivers/gpu/drm/stm/ltdc.h
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 78d7fc0..dd5762a 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -203,7 +203,6 @@ config DRM_VGEM
>> as used by Mesa's software renderer for enhanced performance.
>> If M is selected the module will be called vgem.
>>
>> -
>
> Stray whitespace change.
>
> With this removed, the driver is:
>
> Reviewed-by: Eric Anholt <eric@anholt.net>
>
> Apologies for the delay in the second review offered. The remainder of
> my comments are little cleanups, all of which I think are optional and
> fine to do after the code lands.
>
> You should probably update MAINTAINERS for your new driver. If you'd
> like to maintain this driver in the drm-misc small drivers collection
> (https://01.org/linuxgraphics/gfx-docs/maintainer-tools/drm-misc.html),
> send a follow-up patch to the list to add the MAINTAINERS entry, and I
> can get that and patches 1-4 merged. Once you have a few more patches
> in, we can add you to the drm-misc committers crew so you can merge
> directly after getting review.

Since we are moving sti driver to drm-misc it makes sense to move all
STMicroelectronic SoC display drivers to it.

>
> I'll also take this moment to plug something: Please feel welcome to
> review other people's driver patches on the list. You've built
> something nice here, and probably learned a lot of lessons along the way
> that you could share with others. (I just found out about
> of_reset_control in reviewing your code, and I wish I had known about it
> back when I was landing vc4!)
>
>> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
>> new file mode 100644
>> index 0000000..922f021
>> --- /dev/null
>> +++ b/drivers/gpu/drm/stm/ltdc.c
>
>> +static void ltdc_crtc_disable(struct drm_crtc *crtc)
>> +{
>> + struct ltdc_device *ldev = crtc_to_ltdc(crtc);
>> + struct drm_pending_vblank_event *event = crtc->state->event;
>> +
>> + DRM_DEBUG_DRIVER("\n");
>> +
>> + if (!crtc->enabled) {
>> + DRM_DEBUG_DRIVER("already disabled\n");
>> + return;
>> + }
>
> I think this crtc->enabled is a given for the disable() being called.
>
>> +
>> + drm_crtc_vblank_off(crtc);
>> +
>> + /* disable LTDC */
>> + reg_clear(ldev->regs, LTDC_GCR, GCR_LTDCEN);
>> +
>> + /* disable IRQ */
>> + reg_clear(ldev->regs, LTDC_IER, IER_RRIE | IER_FUIE | IER_TERRIE);
>> +
>> + /* immediately commit disable of layers before switching off LTDC */
>> + reg_set(ldev->regs, LTDC_SRCR, SRCR_IMR);
>> +
>> + if (event) {
>> + crtc->state->event = NULL;
>> +
>> + spin_lock_irq(&crtc->dev->event_lock);
>> + if (crtc->state->active && drm_crtc_vblank_get(crtc) == 0)
>> + drm_crtc_arm_vblank_event(crtc, event);
>> + else
>> + drm_crtc_send_vblank_event(crtc, event);
>> + spin_unlock_irq(&crtc->dev->event_lock);
>> + }
>
> I believe that we're guaranteed that crtc->state->event is NULL in the
> disable call, since your atomic_flush() already armed or sent the event
> and NULLed out the pointer.
>
>> +struct drm_connector *ltdc_rgb_connector_create(struct drm_device *ddev)
>> +{
>> + struct drm_connector *connector;
>> + int err;
>> +
>> + connector = devm_kzalloc(ddev->dev, sizeof(*connector), GFP_KERNEL);
>> + if (!connector) {
>> + DRM_ERROR("Failed to allocate connector\n");
>> + return NULL;
>> + }
>> +
>> + connector->polled = DRM_CONNECTOR_POLL_HPD;
>> +
>> + err = drm_connector_init(ddev, connector, &ltdc_rgb_connector_funcs,
>> + DRM_MODE_CONNECTOR_LVDS);
>
> I think DRM_MODE_CONNECTOR_DPI (and _ENCODER_DPI) are slightly more
> accurate descriptions, if I'm interpreting your pinmux setup right.
> It's cosmetic, though.
>
>> +static struct drm_panel *ltdc_get_panel(struct drm_device *ddev)
>> +{
>> + struct device *dev = ddev->dev;
>> + struct device_node *np = dev->of_node;
>> + struct device_node *entity, *port = NULL;
>> + struct drm_panel *panel = NULL;
>> +
>> + DRM_DEBUG_DRIVER("\n");
>> +
>> + /*
>> + * Parse ltdc node to get remote port and find RGB panel / HDMI slave
>> + * If a dsi or a bridge (hdmi, lvds...) is connected to ltdc,
>> + * a remote port & RGB panel will not be found.
>> + */
>> + for_each_endpoint_of_node(np, entity) {
>> + if (!of_device_is_available(entity))
>> + continue;
>> +
>> + port = of_graph_get_remote_port_parent(entity);
>> + if (port) {
>> + panel = of_drm_find_panel(port);
>> + of_node_put(port);
>> + if (panel) {
>> + DRM_DEBUG_DRIVER("remote panel %s\n",
>> + port->full_name);
>> + } else {
>> + DRM_DEBUG_DRIVER("panel missing\n");
>> + of_node_put(entity);
>> + }
>> + }
>> + }
>
> Future work: You may find the new drm_of_find_panel_or_bridge() useful
> to drop this loop.
>
>> +
>> + return panel;
>> +}
>> +
>> +int ltdc_load(struct drm_device *ddev)
>> +{
>> + struct platform_device *pdev = to_platform_device(ddev->dev);
>> + struct ltdc_device *ldev = ddev->dev_private;
>> + struct device *dev = ddev->dev;
>> + struct device_node *np = dev->of_node;
>> + struct drm_encoder *encoder;
>> + struct drm_connector *connector = NULL;
>> + struct drm_crtc *crtc;
>> + struct reset_control *rstc;
>> + struct resource res;
>> + int irq, ret, i;
>> +
>> + DRM_DEBUG_DRIVER("\n");
>> +
>> + ldev->panel = ltdc_get_panel(ddev);
>> + if (!ldev->panel)
>> + return -EPROBE_DEFER;
>> +
>> + rstc = of_reset_control_get(np, NULL);
>> +
>> + mutex_init(&ldev->err_lock);
>> +
>> + ldev->pixel_clk = devm_clk_get(dev, "lcd");
>> + if (IS_ERR(ldev->pixel_clk)) {
>> + DRM_ERROR("Unable to get lcd clock\n");
>> + return -ENODEV;
>> + }
>> +
>> + if (clk_prepare_enable(ldev->pixel_clk)) {
>> + DRM_ERROR("Unable to prepare pixel clock\n");
>> + return -ENODEV;
>> + }
>
> Future work: You may want to move the pixel clock enable into the CRTC's
> .enable() and disable in .disable(). It sounded in previous versions
> like the HW uses that clock for all register accesses, so you'd need to
> protect a couple of other places, but that should save power when the
> device is off, right?
>
>> +
>> + if (of_address_to_resource(np, 0, &res)) {
>> + DRM_ERROR("Unable to get resource\n");
>> + return -ENODEV;
>> + }
>> +
>> + ldev->regs = devm_ioremap_resource(dev, &res);
>> + if (IS_ERR(ldev->regs)) {
>> + DRM_ERROR("Unable to get ltdc registers\n");
>> + return PTR_ERR(ldev->regs);
>> + }
>> +
>> + for (i = 0; i < MAX_IRQ; i++) {
>> + irq = platform_get_irq(pdev, i);
>> + if (irq < 0)
>> + continue;
>> +
>> + ret = devm_request_threaded_irq(dev, irq, ltdc_irq,
>> + ltdc_irq_thread, IRQF_ONESHOT,
>> + dev_name(dev), ddev);
>> + if (ret) {
>> + DRM_ERROR("Failed to register LTDC interrupt\n");
>> + return ret;
>> + }
>> + }
>> +
>> + if (!IS_ERR(rstc))
>> + reset_control_deassert(rstc);
>> +
>> + /* Disable interrupts */
>> + reg_clear(ldev->regs, LTDC_IER,
>> + IER_LIE | IER_RRIE | IER_FUIE | IER_TERRIE);
>> +
>> + ret = ltdc_get_caps(ddev);
>> + if (ret) {
>> + DRM_ERROR("hardware identifier (0x%08x) not supported!\n",
>> + ldev->caps.hw_version);
>> + return ret;
>> + }
>> +
>> + DRM_INFO("ltdc hw version 0x%08x - ready\n", ldev->caps.hw_version);
>> +
>> + if (ltdc_create_encoders(ddev)) {
>> + DRM_ERROR("Failed to create encoders\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (ldev->panel) {
>> + encoder = ltdc_rgb_encoder_find(ddev);
>> + if (!encoder) {
>> + DRM_ERROR("Failed to find RGB encoder\n");
>> + ret = -EINVAL;
>> + goto err;
>> + }
>
> Given that ltdc_create_encoders() only does work if ldev->panel, its
> body could probably be moved in here and then ltdc_rgb_encoder_find
> could be dropped.
>
>> +
>> + connector = ltdc_rgb_connector_create(ddev);
>> + if (!connector) {
>> + DRM_ERROR("Failed to create RGB connector\n");
>> + ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + ret = drm_mode_connector_attach_encoder(connector, encoder);
>> + if (ret) {
>> + DRM_ERROR("Failed to attach connector to encoder\n");
>> + goto err;
>> + }
>> +
>> + drm_panel_attach(ldev->panel, connector);
>> + }
>
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>

--
Benjamin Gaignard

Graphic Study Group

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