Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753838Ab3JDCqw (ORCPT ); Thu, 3 Oct 2013 22:46:52 -0400 Received: from mail-vc0-f180.google.com ([209.85.220.180]:45141 "EHLO mail-vc0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752427Ab3JDCqt (ORCPT ); Thu, 3 Oct 2013 22:46:49 -0400 MIME-Version: 1.0 In-Reply-To: References: <1380670860-17621-1-git-send-email-seanpaul@chromium.org> <1380839303-4834-1-git-send-email-seanpaul@chromium.org> <1380839303-4834-5-git-send-email-seanpaul@chromium.org> From: Sean Paul Date: Thu, 3 Oct 2013 22:41:27 -0400 Message-ID: Subject: Re: [PATCH v2 4/5] drm/exynos: Initialize ptn3460 if present To: Inki Dae Cc: Kukjin Kim , DRI mailing list , "linux-samsung-soc@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "devicetree@vger.kernel.org" , Dave Airlie Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5055 Lines: 137 On Thu, Oct 3, 2013 at 10:29 PM, Inki Dae wrote: > 2013/10/4 Sean Paul : >> This patch adds code to look for the ptn3460 in the device tree file on >> exynos initialization. If ptn node is found, the driver will initialize >> the ptn3460 driver and skip creating a DP connector (since the bridge >> driver will register its own connector). >> >> Signed-off-by: Sean Paul >> --- >> >> v2: >> - Changed include from of_i2c.h to i2c.h >> - Changed of_find_by_name to of_find_compatible >> >> drivers/gpu/drm/exynos/exynos_drm_core.c | 44 +++++++++++++++++++++++++++++++- >> 1 file changed, 43 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/exynos/exynos_drm_core.c b/drivers/gpu/drm/exynos/exynos_drm_core.c >> index 1bef6dc..08ca4f9 100644 >> --- a/drivers/gpu/drm/exynos/exynos_drm_core.c >> +++ b/drivers/gpu/drm/exynos/exynos_drm_core.c >> @@ -12,7 +12,9 @@ >> * option) any later version. >> */ >> >> +#include >> #include >> +#include >> #include "exynos_drm_drv.h" >> #include "exynos_drm_encoder.h" >> #include "exynos_drm_connector.h" >> @@ -20,6 +22,40 @@ >> >> static LIST_HEAD(exynos_drm_subdrv_list); >> >> +struct bridge_init { >> + struct i2c_client *client; >> + struct device_node *node; >> +}; >> + >> +static bool find_bridge(const char *compat, struct bridge_init *bridge) >> +{ >> + bridge->client = NULL; >> + bridge->node = of_find_compatible_node(NULL, NULL, compat); > > Then, shouldn't the lvds-bridge driver be implemented as i2c driver so > that such tricky isn't needed? Is there any reason you use such tricky > codes? > This is what I was explaining earlier today. If the bridge driver is just an i2c driver, it won't get a pointer to drm_device, and can't register itself as a drm_bridge or drm_connector. To solve this, you need the ptn3460_init callback. If it's an i2c driver with the ptn3460_init callback, where it parses the dt in probe, then you have a race between the ptn probe and the ptn init/drm hooks. ie: it's possible drm will initialize and call disable/post_disable/pre_enable/enable before things have been probed. To solve this, you need to use some global state and/or locking. So, to summarize. We can have this of_find_compatible with a init callback, or we can have an i2c driver + global state/locking + init callback. I chose the former, since it seemed easier. If you have a better way to achieve this, I'm definitely interested, but I saw this as the lesser of two evils. Sean > I think you need to implement the lvds-bridge driver as i2c driver, > and then consider how to take care of this. I mean let's find a better > way how we could take care of the i2c based driver in exynos drm > framework or driver. In all cases, such tricky codes are not good. > >> + if (!bridge->node) >> + return false; >> + >> + bridge->client = of_find_i2c_device_by_node(bridge->node); >> + if (!bridge->client) >> + return false; >> + >> + return true; >> +} >> + >> +/* returns the number of bridges attached */ >> +static int exynos_drm_attach_lcd_bridge(struct drm_device *dev, >> + struct drm_encoder *encoder) >> +{ >> + struct bridge_init bridge; >> + int ret; >> + >> + if (find_bridge("nxp,ptn3460", &bridge)) { >> + ret = ptn3460_init(dev, encoder, bridge.client, bridge.node); >> + if (!ret) >> + return 1; >> + } >> + return 0; >> +} >> + >> static int exynos_drm_create_enc_conn(struct drm_device *dev, >> struct exynos_drm_subdrv *subdrv) >> { >> @@ -36,6 +72,13 @@ static int exynos_drm_create_enc_conn(struct drm_device *dev, >> DRM_ERROR("failed to create encoder\n"); >> return -EFAULT; >> } >> + subdrv->encoder = encoder; >> + >> + if (subdrv->manager->display_ops->type == EXYNOS_DISPLAY_TYPE_LCD) { >> + ret = exynos_drm_attach_lcd_bridge(dev, encoder); >> + if (ret) >> + return 0; >> + } >> >> /* >> * create and initialize a connector for this sub driver and >> @@ -48,7 +91,6 @@ static int exynos_drm_create_enc_conn(struct drm_device *dev, >> goto err_destroy_encoder; >> } >> >> - subdrv->encoder = encoder; >> subdrv->connector = connector; >> >> return 0; >> -- >> 1.8.4 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/