-----Original Message----- From: Thomas Zimmermann [mailto:tzimmermann@xxxxxxx] Sent: Monday, September 20, 2021 4:17 PM To: Kuo-Hsiang Chou <kuohsiang_chou@xxxxxxxxxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx 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! Best Regards, Kuo-Hsiang Chou Best regards Thomas > > Signed-off-by: KuoHsiang Chou <kuohsiang_chou@xxxxxxxxxxxxxx> > --- > 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
