From: Robert Chiras <robert.chiras@xxxxxxx>
This patch adds support for a new clock 'video_pll' in order to better
set the video_pll clock to a clock-rate that satisfies a mode's clock.
The video PLL, on i.MX8MQ, can drive both DC pixel-clock and DSI phy_ref
clock. When used with a bridge that can drive multiple modes, like a DSI
to HDMI bridge, the DSI can't be statically configured for a specific
mode in the DTS file.
So, this patch adds access to the video PLL inside the DSI driver, so
that modes can be filtered-out if the required combination of phy_ref
and pixel-clock can't be achieved using the video PLL.
Signed-off-by: Robert Chiras <robert.chiras@xxxxxxx>
---
drivers/gpu/drm/bridge/nwl-dsi.c | 318 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 313 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
index ce94f79..1228466 100644
--- a/drivers/gpu/drm/bridge/nwl-dsi.c
+++ b/drivers/gpu/drm/bridge/nwl-dsi.c
@@ -39,6 +39,20 @@
#define NWL_DSI_MIPI_FIFO_TIMEOUT msecs_to_jiffies(500)
+/* Maximum Video PLL frequency: 1.2GHz */
+#define MAX_PLL_FREQ 1200000000
+
+#define MBPS(x) ((x) * 1000000)
+#define MIN_PHY_RATE MBPS(24)
+#define MAX_PHY_RATE MBPS(30)
+
+/* Possible valid PHY reference clock rates*/
+static u32 phyref_rates[] = {
+ 27000000,
+ 25000000,
+ 24000000,
+};
+
enum transfer_direction {
DSI_PACKET_SEND,
DSI_PACKET_RECEIVE,
@@ -67,6 +81,17 @@ struct nwl_dsi_transfer {
size_t rx_len; /* in bytes */
};
+struct mode_config {
+ int clock;
+ int crtc_clock;
+ unsigned int lanes;
+ unsigned long bitclock;
+ unsigned long phy_rates[3];
+ unsigned long pll_rates[3];
+ int phy_rate_idx;
+ struct list_head list;
+};
+
struct nwl_dsi {
struct drm_bridge bridge;
struct mipi_dsi_host dsi_host;
@@ -101,6 +126,7 @@ struct nwl_dsi {
struct clk *rx_esc_clk;
struct clk *tx_esc_clk;
struct clk *core_clk;
+ struct clk *pll_clk;
/*
* hardware bug: the i.MX8MQ needs this clock on during reset
* even when not using LCDIF.
@@ -115,6 +141,7 @@ struct nwl_dsi {
int error;
struct nwl_dsi_transfer *xfer;
+ struct list_head valid_modes;
};
static const struct regmap_config nwl_dsi_regmap_config = {
@@ -778,6 +805,207 @@ static void nwl_dsi_bridge_disable(struct drm_bridge *bridge)
pm_runtime_put(dsi->dev);
}
+static unsigned long nwl_dsi_get_bit_clock(struct nwl_dsi *dsi,
+ unsigned long pixclock, u32 lanes)
+{
+ int bpp;
+
+ if (lanes < 1 || lanes > 4)
+ return 0;
+
+ bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
+
+ return (pixclock * bpp) / lanes;
+}
+
+/*
+ * Utility function to calculate least commom multiple, using an improved
+ * version of the Euclidean algorithm for greatest common factor.
+ */
+static unsigned long nwl_dsi_get_lcm(unsigned long a, unsigned long b)
+{
+ u32 gcf = 0; /* greatest common factor */
+ unsigned long tmp_a = a;
+ unsigned long tmp_b = b;
+
+ if (!a || !b)
+ return 0;
+
+ while (tmp_a % tmp_b) {
+ gcf = tmp_a % tmp_b;
+ tmp_a = tmp_b;
+ tmp_b = gcf;
+ }
+
+ if (!gcf)
+ return a;
+
+ return ((unsigned long long)a * b) / gcf;
+}
+
+/*
+ * This function tries to adjust the crtc_clock for a DSI device in such a way
+ * that the video pll will be able to satisfy both Display Controller pixel
+ * clock (feeding out DPI interface) and our input phy_ref clock.
+ */
+static void nwl_dsi_setup_pll_config(struct mode_config *config)
+{
+ unsigned long pll_rate;
+ int div;
+ size_t i, num_rates = ARRAY_SIZE(config->phy_rates);
+
+ config->crtc_clock = 0;
+
+ for (i = 0; i < num_rates; i++) {
+ int crtc_clock;
+
+ if (!config->phy_rates[i])
+ break;
+ /*
+ * First, we need to check if phy_ref can actually be obtained
+ * from pixel clock. To do this, we check their lowest common
+ * multiple, which has to be in PLL range.
+ */
+ pll_rate = nwl_dsi_get_lcm(config->clock, config->phy_rates[i]);
+ if (pll_rate > MAX_PLL_FREQ) {
+ /* Drop pll_rate to a realistic value */
+ while (pll_rate > MAX_PLL_FREQ)
+ pll_rate >>= 1;
+ /* Make sure pll_rate can provide phy_ref rate */
+ div = DIV_ROUND_UP(pll_rate, config->phy_rates[i]);
+ pll_rate = config->phy_rates[i] * div;
+ } else {
+ /*
+ * Increase the pll rate to highest possible rate for
+ * better accuracy.
+ */
+ while (pll_rate <= MAX_PLL_FREQ)
+ pll_rate <<= 1;
+ pll_rate >>= 1;
+ }
+
+ /*
+ * Next, we need to tweak the pll_rate to a value that can also
+ * satisfy the crtc_clock.
+ */
+ div = DIV_ROUND_CLOSEST(pll_rate, config->clock);
+ if (lvl)
+ pll_rate -= config->phy_rates[i] * lvl;
+ crtc_clock = pll_rate / div;
+ config->pll_rates[i] = pll_rate;
+
+ /*
+ * Pick a crtc_clock which is closest to pixel clock.
+ * Also, make sure that the pixel clock is a multiply of
+ * 50Hz.
+ */
+ if (!(crtc_clock % 50) &&
+ abs(config->clock - crtc_clock) <
+ abs(config->clock - config->crtc_clock)) {
+ config->crtc_clock = crtc_clock;
+ config->phy_rate_idx = i;
+ }
+ }
+}
+
+
+/*
+ * This function will try the required phy speed for current mode
+ * If the phy speed can be achieved, the phy will save the speed
+ * configuration
+ */
+static struct mode_config *nwl_dsi_mode_probe(struct nwl_dsi *dsi,
+ const struct drm_display_mode *mode)
+{
+ struct device *dev = dsi->dev;
+ struct mode_config *config;
+ union phy_configure_opts phy_opts;
+ unsigned long clock = mode->clock * 1000;
+ unsigned long bit_clk = 0;
+ unsigned long phy_rates[3] = {0};
+ int match_rates = 0;
+ u32 lanes = dsi->lanes;
+ size_t i = 0, num_rates = ARRAY_SIZE(phyref_rates);
+
+ list_for_each_entry(config, &dsi->valid_modes, list)
+ if (config->clock == clock)
+ return config;
+
+ phy_mipi_dphy_get_default_config(clock,
+ mipi_dsi_pixel_format_to_bpp(dsi->format),
+ lanes, &phy_opts.mipi_dphy);
+ phy_opts.mipi_dphy.lp_clk_rate = clk_get_rate(dsi->tx_esc_clk);
+
+ while (i < num_rates) {
+ int ret;
+
+ bit_clk = nwl_dsi_get_bit_clock(dsi, clock, lanes);
+
+ clk_set_rate(dsi->pll_clk, phyref_rates[i] * 32);
+ clk_set_rate(dsi->phy_ref_clk, phyref_rates[i]);
+ ret = phy_validate(dsi->phy, PHY_MODE_MIPI_DPHY, 0, &phy_opts);
+
+ /* Pick the non-failing rate, and search for more */
+ if (!ret) {
+ phy_rates[match_rates++] = phyref_rates[i++];
+ continue;
+ }
+
+ if (match_rates)
+ break;
+
+ /* Reached the end of phyref_rates, try another lane config */
+ if ((i++ == num_rates - 1) && (--lanes > 2)) {
+ i = 0;
+ continue;
+ }
+ }
+
+ /*
+ * Try swinging between min and max pll rates and see what rate (in terms
+ * of kHz) we can custom use to get the required bit-clock.
+ */
+ if (!match_rates) {
+ int min_div, max_div;
+ int bit_clk_khz;
+
+ lanes = dsi->lanes;
+ bit_clk = nwl_dsi_get_bit_clock(dsi, clock, lanes);
+
+ min_div = DIV_ROUND_UP(bit_clk, MAX_PHY_RATE);
+ max_div = DIV_ROUND_DOWN_ULL(bit_clk, MIN_PHY_RATE);
+ bit_clk_khz = bit_clk / 1000;
+
+ for (i = max_div; i > min_div; i--) {
+ if (!(bit_clk_khz % i)) {
+ phy_rates[0] = bit_clk / i;
+ match_rates = 1;
+ break;
+ }
+ }
+ }
+
+ if (!match_rates) {
+ DRM_DEV_DEBUG_DRIVER(dev,
+ "Cannot setup PHY for mode: %ux%u @%d kHz\n",
+ mode->hdisplay,
+ mode->vdisplay,
+ mode->clock);
+
+ return NULL;
+ }
+
+ config = devm_kzalloc(dsi->dev, sizeof(struct mode_config), GFP_KERNEL);
+ config->clock = clock;
+ config->lanes = lanes;
+ config->bitclock = bit_clk;
+ memcpy(&config->phy_rates, &phy_rates, sizeof(phy_rates));
+ list_add(&config->list, &dsi->valid_modes);
+
+ return config;
+}
+
+
static int nwl_dsi_get_dphy_params(struct nwl_dsi *dsi,
const struct drm_display_mode *mode,
union phy_configure_opts *phy_opts)
@@ -809,6 +1037,38 @@ static bool nwl_dsi_bridge_mode_fixup(struct drm_bridge *bridge,
const struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode)
{
+ struct nwl_dsi *dsi = bridge_to_dsi(bridge);
+ struct mode_config *config;
+ unsigned long pll_rate;
+
+ DRM_DEV_DEBUG_DRIVER(dsi->dev, "Fixup mode:\n");
+ drm_mode_debug_printmodeline(adjusted_mode);
+
+ config = nwl_dsi_mode_probe(dsi, adjusted_mode);
+ if (!config)
+ return false;
+
+ DRM_DEV_DEBUG_DRIVER(dsi->dev, "lanes=%u, data_rate=%lu\n",
+ config->lanes, config->bitclock);
+ if (config->lanes < 2 || config->lanes > 4)
+ return false;
+
+ /* Max data rate for this controller is 1.5Gbps */
+ if (config->bitclock > 1500000000)
+ return false;
+
+ pll_rate = config->pll_rates[config->phy_rate_idx];
+ if (dsi->pll_clk && pll_rate) {
+ clk_set_rate(dsi->pll_clk, pll_rate);
+ DRM_DEV_DEBUG_DRIVER(dsi->dev,
+ "Video pll rate: %lu (actual: %lu)",
+ pll_rate, clk_get_rate(dsi->pll_clk));
+ }
+ /* Update the crtc_clock to be used by display controller */
+ if (config->crtc_clock)
+ adjusted_mode->crtc_clock = config->crtc_clock / 1000;
+
+
/* At least LCDIF + NWL needs active high sync */
adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
@@ -822,14 +1082,29 @@ nwl_dsi_bridge_mode_valid(struct drm_bridge *bridge,
const struct drm_display_mode *mode)
{
struct nwl_dsi *dsi = bridge_to_dsi(bridge);
- int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
+ struct mode_config *config;
+ unsigned long pll_rate;
+ int bit_rate;
- if (mode->clock * bpp > 15000000 * dsi->lanes)
+ bit_rate = nwl_dsi_get_bit_clock(dsi, mode->clock * 1000, dsi->lanes);
+
+ DRM_DEV_DEBUG_DRIVER(dsi->dev, "Validating mode:");
+ drm_mode_debug_printmodeline(mode);
+
+ if (bit_rate > MBPS(1500))
return MODE_CLOCK_HIGH;
- if (mode->clock * bpp < 80000 * dsi->lanes)
+ if (bit_rate < MBPS(80))
return MODE_CLOCK_LOW;
+ config = nwl_dsi_mode_probe(dsi, mode);
+ if (!config)
+ return MODE_NOCLOCK;
+
+ pll_rate = config->pll_rates[config->phy_rate_idx];
+ if (dsi->pll_clk && !pll_rate)
+ nwl_dsi_setup_pll_config(config);
+
return MODE_OK;
}
@@ -842,8 +1117,22 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
struct device *dev = dsi->dev;
union phy_configure_opts new_cfg;
unsigned long phy_ref_rate;
+ struct mode_config *config;
int ret;
+ DRM_DEV_DEBUG_DRIVER(dsi->dev, "Setting mode:\n");
+ drm_mode_debug_printmodeline(adjusted_mode);
+
+ config = nwl_dsi_mode_probe(dsi, adjusted_mode);
+ /* New mode? This should NOT happen */
+ if (!config) {
+ DRM_DEV_ERROR(dsi->dev, "Unsupported mode provided:\n");
+ drm_mode_debug_printmodeline(adjusted_mode);
+ return;
+ }
+
+ phy_ref_rate = config->phy_rates[config->phy_rate_idx];
+ clk_set_rate(dsi->phy_ref_clk, phy_ref_rate);
ret = nwl_dsi_get_dphy_params(dsi, adjusted_mode, &new_cfg);
if (ret < 0)
return;
@@ -855,8 +1144,10 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
if (new_cfg.mipi_dphy.hs_clk_rate == dsi->phy_cfg.mipi_dphy.hs_clk_rate)
return;
- phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
- DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
+ DRM_DEV_DEBUG_DRIVER(dev,
+ "PHY at ref rate: %lu (actual: %lu)\n",
+ phy_ref_rate, clk_get_rate(dsi->phy_ref_clk));
+
/* Save the new desired phy config */
memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
@@ -1014,6 +1305,12 @@ static int nwl_dsi_parse_dt(struct nwl_dsi *dsi)
}
dsi->tx_esc_clk = clk;
+ /* The video_pll clock is optional */
+ clk = devm_clk_get(dsi->dev, "video_pll");
+ if (!IS_ERR(clk))
+ dsi->pll_clk = clk;
+
+
dsi->mux = devm_mux_control_get(dsi->dev, NULL);
if (IS_ERR(dsi->mux)) {
ret = PTR_ERR(dsi->mux);
@@ -1066,6 +1363,9 @@ static int nwl_dsi_parse_dt(struct nwl_dsi *dsi)
PTR_ERR(dsi->rst_dpi));
return PTR_ERR(dsi->rst_dpi);
}
+
+ INIT_LIST_HEAD(&dsi->valid_modes);
+
return 0;
}
@@ -1184,6 +1484,14 @@ static int nwl_dsi_probe(struct platform_device *pdev)
static int nwl_dsi_remove(struct platform_device *pdev)
{
struct nwl_dsi *dsi = platform_get_drvdata(pdev);
+ struct mode_config *config;
+ struct list_head *pos, *tmp;
+
+ list_for_each_safe(pos, tmp, &dsi->valid_modes) {
+ config = list_entry(pos, struct mode_config, list);
+ list_del(pos);
+ devm_kfree(dsi->dev, config);
+ }
nwl_dsi_deselect_input(dsi);
mipi_dsi_host_unregister(&dsi->dsi_host);
--
2.7.4
