| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20250625083651.0f545d44@booty>
Date: Wed, 25 Jun 2025 08:36:51 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Anusha Srivatsa <asrivats@...hat.com>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang
<quic_jesszhan@...cinc.com>, Maarten Lankhorst
<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, Francesco Dolcini <francesco@...cini.it>
Subject: Re: [PATCH] panel/simple-simple: Identify simple DPI panels using
.compatible field
Hello Anusha,
thanks for quickly addressing this issue!
On Tue, 24 Jun 2025 15:13:05 -0500
Anusha Srivatsa <asrivats@...hat.com> wrote:
> Currently driver is checking for desc == &panel_dpi to do the DPI
> specific panel desc allocations. This looks hacky.
>
> The panel allocation in panel_simple_probe() breaks due to not having
> the desc for DPI scenario. This patch does the following:
>
> - Rename panel_dpi_probe() to panel_dpi_get_desc() and call it before
> panel allocation. panel_dpi_get_desc() returns a panel desc unlike
> panel_dpi_probe() which returned an int. This way driver has a known
> connector type while allocating the panel.
> - panel_dpi_get_desc() returns a panel desc
> - Add a simple helper is_panel_dpi() to identify a simple DPI panel from
> a simple panel based on .compatible field
>
> Fixes: de04bb0089a9 ("drm/panel/panel-simple: Use the new allocation in place of devm_kzalloc()")
Please add a mention to the discussion:
Closes: https://lore.kernel.org/all/20250612081834.GA248237@francesco-nb/
and also:
Reported-by: Francesco Dolcini <francesco@...cini.it>
> Suggested-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
> Suggested-by: Maxime Ripard <mripard@...nel.org>
> Cc: Francesco Dolcini <francesco@...cini.it>
> Cc: Luca Ceresoli <luca.ceresoli@...tlin.com>
> Cc: Maxime Ripard <mripard@...nel.org>
> Signed-off-by: Anusha Srivatsa <asrivats@...hat.com>
> ---
> Seeing the below trace due to the changes introduced by:
> Commit de04bb0089a9 ("drm/panel/panel-simple: Use the new allocation in place of devm_kzalloc()")
>
> [ 12.089274] ------------[ cut here ]------------
> [ 12.089303] WARNING: CPU: 0 PID: 96 at drivers/gpu/drm/bridge/panel.c:377 devm_drm_of_get_bridge+0xac/0xb8
> [ 12.130808] Modules linked in: v4l2_jpeg pwm_imx27(+) imx_vdoa gpu_sched panel_simple imx6_media(C) imx_media_common
> (C) videobuf2_dma_contig pwm_bl gpio_keys v4l2_mem2mem fuse ipv6 autofs4
> [ 12.147774] CPU: 0 UID: 0 PID: 96 Comm: kworker/u8:3 Tainted: G C 6.16.0-rc1+ #1 PREEMPT
> [ 12.157446] Tainted: [C]=CRAP
> [ 12.160418] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> [ 12.166953] Workqueue: events_unbound deferred_probe_work_func
> [ 12.172805] Call trace:
> [ 12.172815] unwind_backtrace from show_stack+0x10/0x14
> [ 12.180598] show_stack from dump_stack_lvl+0x68/0x74
> [ 12.185674] dump_stack_lvl from __warn+0x7c/0xe0
> [ 12.190407] __warn from warn_slowpath_fmt+0x1b8/0x1c0
> [ 12.195567] warn_slowpath_fmt from devm_drm_of_get_bridge+0xac/0xb8
> [ 12.201949] devm_drm_of_get_bridge from imx_pd_probe+0x58/0x164
> [ 12.207976] imx_pd_probe from platform_probe+0x5c/0xb0
> [ 12.213220] platform_probe from really_probe+0xd0/0x3a4
> [ 12.218551] really_probe from __driver_probe_device+0x8c/0x1d4
> [ 12.224486] __driver_probe_device from driver_probe_device+0x30/0xc0
> [ 12.230942] driver_probe_device from __device_attach_driver+0x98/0x10c
> [ 12.237572] __device_attach_driver from bus_for_each_drv+0x90/0xe4
> [ 12.243854] bus_for_each_drv from __device_attach+0xa8/0x1c8
> [ 12.249614] __device_attach from bus_probe_device+0x88/0x8c
> [ 12.255285] bus_probe_device from deferred_probe_work_func+0x8c/0xcc
> [ 12.261739] deferred_probe_work_func from process_one_work+0x154/0x2dc
> [ 12.268371] process_one_work from worker_thread+0x250/0x3f0
> [ 12.274043] worker_thread from kthread+0x12c/0x24c
> [ 12.278940] kthread from ret_from_fork+0x14/0x28
> [ 12.283660] Exception stack(0xd0be9fb0 to 0xd0be9ff8)
> [ 12.288720] 9fa0: 00000000 00000000 00000000 00000000
> [ 12.296906] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [ 12.305089] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [ 12.312050] ---[ end trace 0000000000000000 ]---
> ---
> drivers/gpu/drm/panel/panel-simple.c | 38 +++++++++++++++++++++---------------
> 1 file changed, 22 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 0a3b26bb4d731c54614e24e38018c308acd5367a..2e6fd545100388a9d53183a5621e7b8fdb4148ae 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -26,6 +26,7 @@
> #include <linux/i2c.h>
> #include <linux/media-bus-format.h>
> #include <linux/module.h>
> +#include <linux/of_device.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> @@ -432,8 +433,7 @@ static const struct drm_panel_funcs panel_simple_funcs = {
>
> static struct panel_desc panel_dpi;
>
> -static int panel_dpi_probe(struct device *dev,
> - struct panel_simple *panel)
> +static struct panel_desc *panel_dpi_get_desc(struct device *dev)
> {
> struct display_timing *timing;
> const struct device_node *np;
> @@ -445,17 +445,17 @@ static int panel_dpi_probe(struct device *dev,
> np = dev->of_node;
> desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
> if (!desc)
> - return -ENOMEM;
> + return NULL;
>
> timing = devm_kzalloc(dev, sizeof(*timing), GFP_KERNEL);
> if (!timing)
> - return -ENOMEM;
> + return NULL;
>
> ret = of_get_display_timing(np, "panel-timing", timing);
> if (ret < 0) {
> dev_err(dev, "%pOF: no panel-timing node found for \"panel-dpi\" binding\n",
> np);
> - return ret;
> + return NULL;
> }
>
> desc->timings = timing;
> @@ -473,9 +473,7 @@ static int panel_dpi_probe(struct device *dev,
> /* We do not know the connector for the DT node, so guess it */
> desc->connector_type = DRM_MODE_CONNECTOR_DPI;
>
> - panel->desc = desc;
> -
> - return 0;
> + return desc;
> }
>
> #define PANEL_SIMPLE_BOUNDS_CHECK(to_check, bounds, field) \
> @@ -570,6 +568,15 @@ static int panel_simple_override_nondefault_lvds_datamapping(struct device *dev,
> return 0;
> }
>
> +static bool is_panel_dpi(struct device *dev)
> +{
> + const struct of_device_id *match;
> +
> + match = of_match_device(dev->driver->of_match_table, dev);
> +
> + return strcmp(match->compatible, "panel_dpi");
The compatible is panel-dpi, not panel_dpi.
> +}
> +
> static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
> {
> struct panel_simple *panel;
> @@ -579,6 +586,10 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
> u32 bus_flags;
> int err;
>
> + /* Is this simple panel a DPI panel */
> + if (is_panel_dpi(dev))
> + desc = panel_dpi_get_desc(dev);
> +
> panel = devm_drm_panel_alloc(dev, struct panel_simple, base,
> &panel_simple_funcs, desc->connector_type);
> if (IS_ERR(panel))
> @@ -611,16 +622,11 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
> return -EPROBE_DEFER;
> }
>
> - if (desc == &panel_dpi) {
> - /* Handle the generic panel-dpi binding */
> - err = panel_dpi_probe(dev, panel);
> - if (err)
> - goto free_ddc;
> - desc = panel->desc;
> - } else {
> + if (is_panel_dpi(dev))
> + goto free_ddc;
> + else
> if (!of_get_display_timing(dev->of_node, "panel-timing", &dt))
> panel_simple_parse_panel_timing_node(dev, panel, &dt);
> - }
The 'else' becomes unnecessary after a 'if () goto xyz;'
With your changes you should now be able to remove both this entry in
platform_of_match:
/* Must be the last entry */
.compatible = "panel-dpi",
.data = &panel_dpi,
and finally this line:
static struct panel_desc panel_dpi;
Otherwise LGTM.
Luca
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
Powered by blists - more mailing lists