On Wed, 2024-08-28 at 10:10 -0400, Bart Van Assche wrote: > > External email : Please do not click links or open attachments until > you have verified the sender or the content. > On 8/28/24 9:46 AM, Peter Wang (王信友) wrote: > > 1. If only UFS controller core driver should do this, > > What about registers that are not REG_INTERRUPT_ENABLE? > > Since ufshcd_writel has been exported, shouldn't the host > > driver have the authority to control all Host REGs? > > It is not because host drivers can change any host controller > register > that host drivers should take the freedom to modify all host > controller > registers. Modifying host controller registers that are vendor > specific from a host driver seems totally fine to me. I think that > standardized host controller registers should only be modified from > the > UFS driver core. Otherwise the UFS core driver cannot be understood > nor > verified without deep understanding of all the host drivers. > Hi Bart, But what we are discussing is a 'workaround', which might allow modifications to standardized host controller registers, right? > > 2. Set REG_INTERRUPT_ENABLE only when hibernate exit? > > If cause the UniPro link to exit, then it should still be > correct, > > just exiting hibernate early? > > This approach has two disadvantages: > - It requires that even more state information is tracked in struct > ufs_hba. It could utilize a host private structure, like ufs_mtk_host. > - This approach is probably incompatible with the power management > core. > I think that there is code in the power management core for > disabling > interrupts during suspend and reenabling interrupts during resume. > Enabling an interrupt that is already enabled is not allowed. > Power management enable or disable interrupt should through device driver hook, such as suspend/resume callback function? I am not sure because MediaTek's power management does not directly control interrupts. > In general, disabling / reenabling interrupts is something that > should > be avoided because it is not compatible with multithreading. The > reason > why it works in the UFS driver for UIC commands is because these are > serialized. Yes, but entering and exiting hibernate are protected by clock gating or the runtime/system PM framework. There shouldn't be issues with multiple threads entering or exiting hibernate? Thanks. Peter > > Thanks, > > Bart.
