dvfm effect on LCD continue

最新推荐文章于 2024-02-29 14:12:43 发布

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最新推荐文章于 2024-02-29 14:12:43 发布

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分类专栏： android 文章标签： patch

本文链接：https://blog.youkuaiyun.com/flybirdlong/article/details/4250231

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本文介绍了一种针对LCD闪烁问题的解决方案。当内核更新到最新版本后，在测试修复LCD闪烁的补丁时，需要根据HSS（水平同步信号）的变化设置PCD（像素时钟除频）。具体来说，当HSS从低变高时先设置PCD，再更新HSS；而当HSS从高变低时，则在更新HSS之后设置PCD。这样可以确保像素时钟频率不会在频率变化过程中增加到原始值以上。

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After the kernel is updated to latest version, during the test on the patch, for fixing the lcd flickering, just set pcd before hss is updated when hss is changed from low to high. and set pcd after hss is changed from high to low.

if (old->hss < new->hss)
pxafb_set_pcd();

        accr &= ~(mask | mask2);
        accr |= data | data2;
        __raw_writel(accr, info->clkmgr_base + ACCR_OFF);
        /* wait until ACSR is changed */
        do {
                accr = __raw_readl(info->clkmgr_base + ACCR_OFF);
                acsr = __raw_readl(info->clkmgr_base + ACSR_OFF);
        } while ((((accr & mask) != data) || ((acsr & mask) != data))
                || ((accr & ACCR_VAUFS_MASK) >> ACCR_VAUFS_OFFSET
                != (acsr & ACSR_VAUFS_MASK) >> ACSR_VAUFS_OFFSET));

        /* set PCD after HSS updated for the case we are moving from a high freq to a lower freq. This way we will
         * assure that the pclk frequency will not increase the original value in the frequency change process*/
        if (old->hss >= new->hss)
                pxafb_set_pcd();

LCD is using sharp