diff mbox series

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

Message ID 1630325486-11741-1-git-send-email-peter.wang@mediatek.com (mailing list archive)
State New, archived
Headers show
Series [v1] scsi: ufs: ufs-mediatek: Change dbg select by check hw version | expand

Commit Message

Peter Wang (王信友) Aug. 30, 2021, 12:11 p.m. UTC 
From: Peter Wang <peter.wang@mediatek.com>

Mediatek UFS dbg select setting is changed in new HW version.
This patch check the HW version before set dbg select.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
---
 drivers/scsi/ufs/ufs-mediatek.c |   22 ++++++++++++++++++++--
 drivers/scsi/ufs/ufs-mediatek.h |    4 ++++
 2 files changed, 24 insertions(+), 2 deletions(-)

Comments

Bart Van Assche Aug. 31, 2021, 2:47 a.m. UTC | #1 
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.
Peter Wang (王信友) Sept. 1, 2021, 2:29 a.m. UTC | #2 
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.
Bart Van Assche Sept. 1, 2021, 2:55 a.m. UTC | #3 
On 8/31/21 19:29, Peter Wang wrote:
> 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.

Hi Peter,

The above can be concluded easily by a human but not by software. If 
this code is analyzed with KCSAN then KCSAN will probably complain. See 
also Documentation/dev-tools/kcsan.rst.

Anyway, I'm fine with this patch.

Thanks,

Bart.
Peter Wang (王信友) Sept. 1, 2021, 5:45 a.m. UTC | #4 
Hi Bart,

Really appreciate your reminder.
We will upload new patch to bypss KCSAN.
Thank you very much.

Peter 


On Tue, 2021-08-31 at 19:55 -0700, Bart Van Assche wrote:
> On 8/31/21 19:29, Peter Wang wrote:
> > 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.
> 
> Hi Peter,
> 
> The above can be concluded easily by a human but not by software. If 
> this code is analyzed with KCSAN then KCSAN will probably complain.
> See 
> also Documentation/dev-tools/kcsan.rst.
> 
> Anyway, I'm fine with this patch.
> 
> Thanks,
> 
> Bart.
diff mbox series

Patch

diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
index d2c2516..c7c18d8 100644
--- a/drivers/scsi/ufs/ufs-mediatek.c
+++ b/drivers/scsi/ufs/ufs-mediatek.c
@@ -296,6 +296,24 @@  static void ufs_mtk_setup_ref_clk_wait_us(struct ufs_hba *hba,
 	host->ref_clk_ungating_wait_us = ungating_us;
 }
 
+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);
+	}
+}
+
 static int ufs_mtk_wait_link_state(struct ufs_hba *hba, u32 state,
 				   unsigned long max_wait_ms)
 {
@@ -305,7 +323,7 @@  static int ufs_mtk_wait_link_state(struct ufs_hba *hba, u32 state,
 	timeout = ktime_add_ms(ktime_get(), max_wait_ms);
 	do {
 		time_checked = ktime_get();
-		ufshcd_writel(hba, 0x20, REG_UFS_DEBUG_SEL);
+		ufs_mtk_dbg_sel(hba);
 		val = ufshcd_readl(hba, REG_UFS_PROBE);
 		val = val >> 28;
 
@@ -1001,7 +1019,7 @@  static void ufs_mtk_dbg_register_dump(struct ufs_hba *hba)
 			 "MPHY Ctrl ");
 
 	/* Direct debugging information to REG_MTK_PROBE */
-	ufshcd_writel(hba, 0x20, REG_UFS_DEBUG_SEL);
+	ufs_mtk_dbg_sel(hba);
 	ufshcd_dump_regs(hba, REG_UFS_PROBE, 0x4, "Debug Probe ");
 }
 
diff --git a/drivers/scsi/ufs/ufs-mediatek.h b/drivers/scsi/ufs/ufs-mediatek.h
index 3f0d3bb..10da6e3 100644
--- a/drivers/scsi/ufs/ufs-mediatek.h
+++ b/drivers/scsi/ufs/ufs-mediatek.h
@@ -18,6 +18,10 @@ 
 #define REG_UFS_REJECT_MON          0x22AC
 #define REG_UFS_DEBUG_SEL           0x22C0
 #define REG_UFS_PROBE               0x22C8
+#define REG_UFS_DEBUG_SEL_B0        0x22D0
+#define REG_UFS_DEBUG_SEL_B1        0x22D4
+#define REG_UFS_DEBUG_SEL_B2        0x22D8
+#define REG_UFS_DEBUG_SEL_B3        0x22DC
 
 /*
  * Ref-clk control