Re: [PATCH v1] scsi: ufs: ufs-mediatek: Change dbg select by check hw version

[Peter Wang <peter.wang@mediatek.com>]

Hi Bart,

REG_UFS_MTK_HW_VER is a read only mediatek dedicated register.
So, hw_ver will get a const value for mediatek to decide how to use
debug select. It only need read once, no need multi-threads protected.

Thanks
Peter


On Mon, 2021-08-30 at 19:47 -0700, Bart Van Assche wrote:
> On 8/30/21 05:11, peter.wang@mediatek.com wrote:
> > +static void ufs_mtk_dbg_sel(struct ufs_hba *hba)
> > +{
> > +	static u32 hw_ver;
> > +
> > +	if (!hw_ver)
> > +		hw_ver = ufshcd_readl(hba, REG_UFS_MTK_HW_VER);
> > +
> > +	if (((hw_ver >> 16) & 0xFF) >= 0x36) {
> > +		ufshcd_writel(hba, 0x820820, REG_UFS_DEBUG_SEL);
> > +		ufshcd_writel(hba, 0x0, REG_UFS_DEBUG_SEL_B0);
> > +		ufshcd_writel(hba, 0x55555555, REG_UFS_DEBUG_SEL_B1);
> > +		ufshcd_writel(hba, 0xaaaaaaaa, REG_UFS_DEBUG_SEL_B2);
> > +		ufshcd_writel(hba, 0xffffffff, REG_UFS_DEBUG_SEL_B3);
> > +	} else {
> > +		ufshcd_writel(hba, 0x20, REG_UFS_DEBUG_SEL);
> > +	}
> > +}
> 
> Can ufs_mtk_dbg_sel() be called from multiple threads at the same
> time? 
> Does the 'hw_ver' variable need to be protected against concurrent
> writes?
> 
> Thanks,
> 
> Bart.