-----Original Message----- From: Kuo-Hsiang Chou Sent: Thursday, September 30, 2021 3:19 PM To: Thomas Zimmermann tzimmermann@suse.de; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH] drm/ast: Atomic CR/SR reg R/W

Hi

-----Original Message----- From: Thomas Zimmermann [mailto:tzimmermann@suse.de] Sent: Monday, September 20, 2021 4:17 PM To: Kuo-Hsiang Chou kuohsiang_chou@aspeedtech.com; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/ast: Atomic CR/SR reg R/W

Hi

Am 17.09.21 um 09:22 schrieb KuoHsiang Chou:

1. Avoid IO-index racing
2. IO-index racing happened on resolustion switching and mouse moving at the same time
3. System hung while IO-index racing occurred.

I'd say that there's something else going one here. Mode setting and cursor movement should be protected against each other by DRM locking. Changing these low-level functions would not solve the issues. I'll try to reproduce the problem ASAP.

Hi Thomas,

Sorry to interrupt you again! May I understand the review's situation? Thanks!

Hi Tomas, Good day! May I understand the review status, or is there anything I can do to improve it? Thanks!

Best Regards, Kuo-Hsiang Chou

Best Regards, Kuo-Hsiang Chou

Best regards Thomas

Signed-off-by: KuoHsiang Chou kuohsiang_chou@aspeedtech.com

drivers/gpu/drm/ast/ast_main.c | 48 +++++++++++++++++++++++++--------- 1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c index 79a361867..1d8fa70c5 100644 --- a/drivers/gpu/drm/ast/ast_main.c +++ b/drivers/gpu/drm/ast/ast_main.c @@ -41,28 +41,52 @@ void ast_set_index_reg_mask(struct ast_private *ast, uint32_t base, uint8_t index, uint8_t mask, uint8_t val) {

• u8 tmp;
• ast_io_write8(ast, base, index);
• tmp = (ast_io_read8(ast, base + 1) & mask) | val;
• ast_set_index_reg(ast, base, index, tmp);

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• jData &= mask;

• jData |= val;

• usData = ((uint16_t) jData << 8) | (uint16_t) index;

• ast_io_write16(ast, base, usData); }

  uint8_t ast_get_index_reg(struct ast_private *ast, uint32_t base, uint8_t index) {

• uint8_t ret;
• ast_io_write8(ast, base, index);
• ret = ast_io_read8(ast, base + 1);
• return ret;

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• return jData; }

  uint8_t ast_get_index_reg_mask(struct ast_private *ast, uint32_t base, uint8_t index, uint8_t mask) {

• uint8_t ret;
• ast_io_write8(ast, base, index);
• ret = ast_io_read8(ast, base + 1) & mask;
• return ret;

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• jData &= mask;

• return jData; }

  static void ast_detect_config_mode(struct drm_device *dev, u32

*scu_rev)

2.18.4

-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer

Hi

-----Original Message----- From: Thomas Zimmermann [mailto:tzimmermann@suse.de] Sent: Friday, December 03, 2021 4:47 PM To: Kuo-Hsiang Chou kuohsiang_chou@aspeedtech.com; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/ast: Atomic CR/SR reg R/W

Hi

Am 03.12.21 um 02:23 schrieb Kuo-Hsiang Chou:

-----Original Message----- From: Kuo-Hsiang Chou Sent: Thursday, September 30, 2021 3:19 PM To: Thomas Zimmermann tzimmermann@suse.de; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH] drm/ast: Atomic CR/SR reg R/W

Hi

-----Original Message----- From: Thomas Zimmermann [mailto:tzimmermann@suse.de] Sent: Monday, September 20, 2021 4:17 PM To: Kuo-Hsiang Chou kuohsiang_chou@aspeedtech.com; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/ast: Atomic CR/SR reg R/W

Hi

Am 17.09.21 um 09:22 schrieb KuoHsiang Chou:

...

1. Avoid IO-index racing
2. IO-index racing happened on resolustion switching and mouse moving at the same time 3. System hung while IO-index

racing occurred.

I'd say that there's something else going one here. Mode setting and cursor movement should be protected against each other by DRM locking. Changing these low-level functions would not solve the issues. I'll try to reproduce the problem ASAP.

Hi Thomas,

Sorry to interrupt you again! May I understand the review's situation? Thanks!

Hi Thomas,

Look, you really have to work with us during the review process. Don't just expect us to tell you what to do. Thanks! Got it.

I'm not going to merge this patch. As I said, I don't think it fixes the problem. Mouse movement and resolution switching should not interfere with each other. The DRM framework should guarantee that. OK, thanks for your confirmation.

I cannot reproduce the issue, but there's most likely something else happening here. How can the system switch resolution and change the mouse at the same time? Sure, we will check if there is a 100 percent method to reproduce the issue. Thanks for your responses.

Regards, Kuo-Hsiang Chou

Best regards Thomas

Hi Tomas, Good day! May I understand the review status, or is there anything I can do to improve it? Thanks!

Best Regards, Kuo-Hsiang Chou

Best Regards, Kuo-Hsiang Chou

Best regards Thomas

...

Signed-off-by: KuoHsiang Chou kuohsiang_chou@aspeedtech.com

drivers/gpu/drm/ast/ast_main.c | 48 +++++++++++++++++++++++++--------- 1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c index 79a361867..1d8fa70c5 100644 --- a/drivers/gpu/drm/ast/ast_main.c +++ b/drivers/gpu/drm/ast/ast_main.c @@ -41,28 +41,52 @@ void ast_set_index_reg_mask(struct ast_private *ast, uint32_t base, uint8_t index, uint8_t mask, uint8_t val) {

• u8 tmp;
• ast_io_write8(ast, base, index);
• tmp = (ast_io_read8(ast, base + 1) & mask) | val;
• ast_set_index_reg(ast, base, index, tmp);

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• jData &= mask;

• jData |= val;

• usData = ((uint16_t) jData << 8) | (uint16_t) index;

• ast_io_write16(ast, base, usData); }

  uint8_t ast_get_index_reg(struct ast_private *ast, uint32_t base, uint8_t index) {

• uint8_t ret;
• ast_io_write8(ast, base, index);
• ret = ast_io_read8(ast, base + 1);
• return ret;

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• return jData; }

  uint8_t ast_get_index_reg_mask(struct ast_private *ast, uint32_t base, uint8_t index, uint8_t mask) {

• uint8_t ret;
• ast_io_write8(ast, base, index);
• ret = ast_io_read8(ast, base + 1) & mask;
• return ret;

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• jData &= mask;

• return jData; }

  static void ast_detect_config_mode(struct drm_device *dev, u32

*scu_rev)

2.18.4

-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer

-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev

Hi Thomas,

Thanks for your kindly assistance.

Regards Kuo-Hsiang Chou

-----Original Message----- From: Thomas Zimmermann [mailto:tzimmermann@suse.de] Sent: Monday, May 02, 2022 10:33 PM To: Kuo-Hsiang Chou kuohsiang_chou@aspeedtech.com; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Cc: Ryan Chen ryan_chen@aspeedtech.com; airlied@linux.ie; 清水修(o-shimizu)-台灣NEC o-shimizu@nec.com.tw; Jenmin Yuan jenmin_yuan@aspeedtech.com; airlied@redhat.com; Arc Sung arc_sung@aspeedtech.com; Luke Chen luke_chen@aspeedtech.com Subject: Re: [PATCH] drm/ast: Atomic CR/SR reg R/W

Hi

Am 06.12.21 um 02:38 schrieb Kuo-Hsiang Chou:

I'm not going to merge this patch. As I said, I don't think it fixes the problem. Mouse movement and resolution switching should not interfere with each other. The DRM framework should guarantee that. OK, thanks for your confirmation.

I cannot reproduce the issue, but there's most likely something else happening here. How can the system switch resolution and change the mouse at the same time? Sure, we will check if there is a 100 percent method to reproduce the issue. Thanks for your responses.

I've been away for a while; sorry for all this taking so long. I've meanwhile been able to reproduce the problem. It happens when GNOME concurrently tries to set the video mode and read the available video modes from EDID. Reading EDID is not protected against concurrent mode setting or cursor movement.

I've posted a patchset that should fix the problem. See [1].

Best regards Thomas

[1] https://lore.kernel.org/dri-devel/20220502142514.2174-1-tzimmermann@suse.de/...

Regards, Kuo-Hsiang Chou

Best regards Thomas

...

Hi Tomas, Good day! May I understand the review status, or is there anything I can do to improve it? Thanks!

Best Regards, Kuo-Hsiang Chou

Best Regards, Kuo-Hsiang Chou

Best regards Thomas

...

Signed-off-by: KuoHsiang Chou kuohsiang_chou@aspeedtech.com

drivers/gpu/drm/ast/ast_main.c | 48 +++++++++++++++++++++++++---------
1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c index 79a361867..1d8fa70c5 100644 --- a/drivers/gpu/drm/ast/ast_main.c +++ b/drivers/gpu/drm/ast/ast_main.c @@ -41,28 +41,52 @@ void ast_set_index_reg_mask(struct ast_private *ast, uint32_t base, uint8_t index, uint8_t mask, uint8_t val) {

• u8 tmp;
• ast_io_write8(ast, base, index);
• tmp = (ast_io_read8(ast, base + 1) & mask) | val;
• ast_set_index_reg(ast, base, index, tmp);

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• jData &= mask;

• jData |= val;

• usData = ((uint16_t) jData << 8) | (uint16_t) index;

• ast_io_write16(ast, base, usData); }

  uint8_t ast_get_index_reg(struct ast_private *ast, uint32_t base, uint8_t index) {

• uint8_t ret;
• ast_io_write8(ast, base, index);
• ret = ast_io_read8(ast, base + 1);
• return ret;

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• return jData; }

  uint8_t ast_get_index_reg_mask(struct ast_private *ast, uint32_t base, uint8_t index, uint8_t mask) {

• uint8_t ret;
• ast_io_write8(ast, base, index);
• ret = ast_io_read8(ast, base + 1) & mask;
• return ret;

• uint16_t volatile usData;

• uint8_t volatile jData;

• do {

• ast_io_write8(ast, base, index);
  

• usData = ast_io_read16(ast, base);
  

• } while ((uint8_t)(usData) != index);

• jData = (uint8_t)(usData >> 8);

• jData &= mask;

• return jData; }

  static void ast_detect_config_mode(struct drm_device *dev, u32

*scu_rev)

2.18.4

-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer

-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev

-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev