| 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: <e02c03ba-1a95-45bb-9291-5b247333f55d@suse.de>
Date: Mon, 10 Nov 2025 08:17:54 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Shixiong Ou <oushixiong@...inos.cn>, oushixiong1025@....com,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Cc: Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, Tiger Liu <liuyihu@...inos.cn>
Subject: Re: [PATCH] drm/fb-helper: add fbdev screen expended mode display
support
Hi
Am 10.11.25 um 06:54 schrieb Shixiong Ou:
>
> 在 2025/11/7 18:06, Thomas Zimmermann 写道:
>>
>>
>> Am 07.11.25 um 10:26 schrieb oushixiong1025@....com:
>>> From: Shixiong Ou <oushixiong@...inos.cn>
>>>
>>> Add fbdev screen extended mode display support
>>
>> What? What is this about?
>>
> If an fbdev device has multiple screens, they are mirrored by default.
> This patch aims to enable extended display for the tty, allowing
> horizontal or
> vertical expansion to achieve a screen splicing effect in the tty
> terminal.
We won't merge that. The mirroring happens because we cannot easily say
which display is the correct one. But the console is a necessity that we
cannot not provide. Its code is already badly maintained and overly
complicated for what it does. Therefore in the framebuffer console we
want to reduce complexity, not add more.
If you want complex screen layouts, please implement a console in user
space or use a compositor.
Best regards
Thomas
>
> Best regards,
> Shixiong
>
>>>
>>> Signed-off-by: Tiger Liu <liuyihu@...inos.cn>
>>> Signed-off-by: Shixiong Ou <oushixiong@...inos.cn>
>>> ---
>>> drivers/gpu/drm/drm_fb_helper.c | 143
>>> ++++++++++++++++++++++++++++++--
>>> 1 file changed, 135 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c
>>> b/drivers/gpu/drm/drm_fb_helper.c
>>> index 53e9dc0543de..a6ec03bf3aef 100644
>>> --- a/drivers/gpu/drm/drm_fb_helper.c
>>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>>> @@ -78,6 +78,17 @@ MODULE_PARM_DESC(drm_leak_fbdev_smem,
>>> "Allow unsafe leaking fbdev physical smem address
>>> [default=false]");
>>> #endif
>>> +#define SCREEN_CLONE 0x0
>>> +#define SCREEN_EXPAND_HORIZONTAL 0x1
>>> +#define SCREEN_EXPAND_VERTICAL 0x2
>>> +
>>> +static bool drm_fbdev_screen_expand_mode_enabled;
>>> +static int drm_fbdev_screen_mode = SCREEN_CLONE;
>>> +module_param_named(screen_mode, drm_fbdev_screen_mode, int, 0444);
>>> +MODULE_PARM_DESC(screen_mode,
>>> + "Screen display of the fbdev. [0 = clone(default), 1 =
>>> expand horizontally,"
>>> + "2 = expand vertically]");
>>> +
>>> static LIST_HEAD(kernel_fb_helper_list);
>>> static DEFINE_MUTEX(kernel_fb_helper_lock);
>>> @@ -1345,15 +1356,35 @@ int drm_fb_helper_set_par(struct fb_info
>>> *info)
>>> }
>>> EXPORT_SYMBOL(drm_fb_helper_set_par);
>>> -static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
>>> +static void pan_set_locked(struct drm_client_dev *client,
>>> + int dx, int dy)
>>> {
>>> struct drm_mode_set *mode_set;
>>> + int screen_x_offset = dx;
>>> + int screen_y_offset = dy;
>>> - mutex_lock(&fb_helper->client.modeset_mutex);
>>> - drm_client_for_each_modeset(mode_set, &fb_helper->client) {
>>> - mode_set->x += dx;
>>> - mode_set->y += dy;
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + if (drm_fbdev_screen_expand_mode_enabled) {
>>> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
>>> + mode_set->x += screen_x_offset;
>>> + mode_set->y += screen_y_offset;
>>> + screen_x_offset += mode_set->mode->hdisplay;
>>> + } else if (drm_fbdev_screen_mode ==
>>> SCREEN_EXPAND_VERTICAL) {
>>> + mode_set->x += screen_x_offset;
>>> + mode_set->y += screen_y_offset;
>>> + screen_y_offset += mode_set->mode->vdisplay;
>>> + }
>>> + } else {
>>> + mode_set->x = screen_x_offset;
>>> + mode_set->y = screen_y_offset;
>>> + }
>>> }
>>> +}
>>> +
>>> +static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
>>> +{
>>> + mutex_lock(&fb_helper->client.modeset_mutex);
>>> + pan_set_locked(&fb_helper->client, dx, dy);
>>> mutex_unlock(&fb_helper->client.modeset_mutex);
>>> }
>>> @@ -1387,10 +1418,8 @@ static int pan_display_legacy(struct
>>> fb_var_screeninfo *var,
>>> mutex_lock(&client->modeset_mutex);
>>> drm_modeset_lock_all(fb_helper->dev);
>>> + pan_set_locked(client, var->xoffset, var->yoffset);
>>> drm_client_for_each_modeset(modeset, client) {
>>> - modeset->x = var->xoffset;
>>> - modeset->y = var->yoffset;
>>> -
>>> if (modeset->num_connectors) {
>>> ret = drm_mode_set_config_internal(modeset);
>>> if (!ret) {
>>> @@ -1461,6 +1490,94 @@ static uint32_t
>>> drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const
>>> return DRM_FORMAT_INVALID;
>>> }
>>> +/*
>>> + * Check if the device supports extended mode
>>> + *
>>> + * return true if the device supports extended mode,
>>> + * otherwise return false.
>>> + */
>>> +static bool drm_fb_helper_validate_extended_mode(struct
>>> drm_fb_helper *fb_helper,
>>> + struct drm_fb_helper_surface_size *sizes)
>>> +{
>>> + struct drm_client_dev *client = &fb_helper->client;
>>> + struct drm_device *dev = fb_helper->dev;
>>> + struct drm_mode_config *config = &dev->mode_config;
>>> + struct drm_mode_set *mode_set;
>>> + u32 crtc_count;
>>> +
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + crtc_count++;
>>> +
>>> + for (int j = 0; j < mode_set->num_connectors; j++) {
>>> + struct drm_connector *connector = mode_set->connectors[j];
>>> +
>>> + if (connector->has_tile) {
>>> + drm_dbg_kms(client->dev,
>>> + "Don't support extended with tile mode
>>> connector yet\n");
>>> + return false;
>>> + }
>>> + }
>>> + }
>>> +
>>> + if (crtc_count < 2) {
>>> + drm_dbg_kms(client->dev,
>>> + "Only support extended mode when device have
>>> mult-crtcs\n");
>>> + return false;
>>> + }
>>> +
>>> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
>>> + u32 x = 0;
>>> +
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + struct drm_display_mode *desired_mode;
>>> +
>>> + desired_mode = mode_set->mode;
>>> + x = mode_set->x;
>>> + sizes->fb_width = sizes->surface_width +=
>>> desired_mode->hdisplay;
>>> + sizes->surface_height =
>>> + min_t(u32, desired_mode->vdisplay + mode_set->y,
>>> + sizes->surface_height);
>>> + sizes->fb_height = min_t(u32, desired_mode->vdisplay +
>>> mode_set->y,
>>> + sizes->fb_height);
>>> + }
>>> + sizes->fb_width = sizes->surface_width += x;
>>> +
>>> + if (sizes->fb_width > config->max_width) {
>>> + drm_dbg_kms(client->dev,
>>> + "screen_buffer total width %d > config width
>>> %d\n",
>>> + sizes->fb_width, config->max_width);
>>> + return false;
>>> + }
>>> + } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
>>> + u32 y = 0;
>>> +
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + struct drm_display_mode *desired_mode;
>>> +
>>> + desired_mode = mode_set->mode;
>>> + y = mode_set->y;
>>> + sizes->fb_height = sizes->surface_height +=
>>> desired_mode->vdisplay;
>>> + sizes->surface_width =
>>> + min_t(u32, desired_mode->hdisplay + mode_set->x,
>>> + sizes->surface_width);
>>> + sizes->fb_width = min_t(u32, desired_mode->hdisplay +
>>> mode_set->x,
>>> + sizes->fb_width);
>>> + }
>>> + sizes->fb_height = sizes->surface_height += y;
>>> +
>>> + if (sizes->fb_height > config->max_height) {
>>> + drm_dbg_kms(client->dev,
>>> + "screen_buffer_total_height %d > config height
>>> %d\n",
>>> + sizes->fb_height, config->max_height);
>>> + return false;
>>> + }
>>> + } else {
>>> + return false;
>>> + }
>>> +
>>> + return true;
>>> +}
>>> +
>>> static int __drm_fb_helper_find_sizes(struct drm_fb_helper
>>> *fb_helper,
>>> struct drm_fb_helper_surface_size *sizes)
>>> {
>>> @@ -1527,6 +1644,16 @@ static int __drm_fb_helper_find_sizes(struct
>>> drm_fb_helper *fb_helper,
>>> /* first up get a count of crtcs now in use and new
>>> min/maxes width/heights */
>>> crtc_count = 0;
>>> +
>>> + /* Check if we support extended mode. If we do, we will adjust
>>> the sizes accordingly. */
>>> + if (drm_fbdev_screen_mode &&
>>> + drm_fb_helper_validate_extended_mode(fb_helper, sizes)) {
>>> + drm_fbdev_screen_expand_mode_enabled = true;
>>> + drm_dbg_kms(dev, "Extended mode: horizontal expansion,
>>> width: %d, height: %d\n",
>>> + sizes->surface_width, sizes->surface_height);
>>> + return 0;
>>> + }
>>> +
>>> drm_client_for_each_modeset(mode_set, client) {
>>> struct drm_display_mode *desired_mode;
>>> int x, y, j;
>>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
Powered by blists - more mailing lists