Re: [PATCH] i2c: tegra: Wait for config load atomically while in ISR

2021-01-11 Thread Mikko Perttunen 

On 1/11/21 5:14 PM, Dmitry Osipenko wrote:

11.01.2021 16:55, Mikko Perttunen пишет:

Upon a communication error, the interrupt handler can call
tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen
unless the current transaction was marked atomic. Since
tegra_i2c_disable_packet_mode is only called from the interrupt path,
make it use atomic waiting always.

Fixes: ede2299f7101 ("i2c: tegra: Support atomic transfers")
Cc: sta...@vger.kernel.org
Signed-off-by: Mikko Perttunen 
---
This fixes constant spew for me while HDMI is connected to a
powered off television.

  drivers/i2c/busses/i2c-tegra.c | 16 
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 6f08c0c3238d..4a7ff1840565 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -528,12 +528,12 @@ static void tegra_i2c_vi_init(struct tegra_i2c_dev 
*i2c_dev)
  
  static int tegra_i2c_poll_register(struct tegra_i2c_dev *i2c_dev,

   u32 reg, u32 mask, u32 delay_us,
-  u32 timeout_us)
+  u32 timeout_us, bool force_atomic)
  {
void __iomem *addr = i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg);
u32 val;
  
-	if (!i2c_dev->atomic_mode)

+   if (!i2c_dev->atomic_mode && !force_atomic)
return readl_relaxed_poll_timeout(addr, val, !(val & mask),
  delay_us, timeout_us);
  
@@ -560,7 +560,7 @@ static int tegra_i2c_flush_fifos(struct tegra_i2c_dev *i2c_dev)

val |= mask;
i2c_writel(i2c_dev, val, offset);
  
-	err = tegra_i2c_poll_register(i2c_dev, offset, mask, 1000, 100);

+   err = tegra_i2c_poll_register(i2c_dev, offset, mask, 1000, 100, 
false);
if (err) {
dev_err(i2c_dev->dev, "failed to flush FIFO\n");
return err;
@@ -569,7 +569,7 @@ static int tegra_i2c_flush_fifos(struct tegra_i2c_dev 
*i2c_dev)
return 0;
  }
  
-static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev)

+static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev, bool 
force_atomic)
  {
int err;
  
@@ -579,7 +579,7 @@ static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev)

i2c_writel(i2c_dev, I2C_MSTR_CONFIG_LOAD, I2C_CONFIG_LOAD);
  
  	err = tegra_i2c_poll_register(i2c_dev, I2C_CONFIG_LOAD, 0x,

- 1000, I2C_CONFIG_LOAD_TIMEOUT);
+ 1000, I2C_CONFIG_LOAD_TIMEOUT, 
force_atomic);
if (err) {
dev_err(i2c_dev->dev, "failed to load config\n");
return err;
@@ -684,7 +684,7 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
if (i2c_dev->multimaster_mode && i2c_dev->hw->has_slcg_override_reg)
i2c_writel(i2c_dev, I2C_MST_CORE_CLKEN_OVR, I2C_CLKEN_OVERRIDE);
  
-	err = tegra_i2c_wait_for_config_load(i2c_dev);

+   err = tegra_i2c_wait_for_config_load(i2c_dev, false);
if (err)
return err;
  
@@ -707,7 +707,7 @@ static int tegra_i2c_disable_packet_mode(struct tegra_i2c_dev *i2c_dev)

if (cnfg & I2C_CNFG_PACKET_MODE_EN)
i2c_writel(i2c_dev, cnfg & ~I2C_CNFG_PACKET_MODE_EN, I2C_CNFG);
  
-	return tegra_i2c_wait_for_config_load(i2c_dev);

+   return tegra_i2c_wait_for_config_load(i2c_dev, true);
  }
  
  static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)

@@ -1090,7 +1090,7 @@ static int tegra_i2c_issue_bus_clear(struct i2c_adapter 
*adap)
  I2C_BC_TERMINATE;
i2c_writel(i2c_dev, val, I2C_BUS_CLEAR_CNFG);
  
-	err = tegra_i2c_wait_for_config_load(i2c_dev);

+   err = tegra_i2c_wait_for_config_load(i2c_dev, false);
if (err)
return err;
  



What about a simpler variant:

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 6f08c0c3238d..0727383f4940 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -533,7 +533,7 @@ static int tegra_i2c_poll_register(struct
tegra_i2c_dev *i2c_dev,
void __iomem *addr = i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg);
u32 val;

-   if (!i2c_dev->atomic_mode)
+   if (!i2c_dev->atomic_mode && !in_irq())
return readl_relaxed_poll_timeout(addr, val, !(val & mask),
  delay_us, timeout_us);



Yep, I'll post a v2 with that.

Mikko

Re: [PATCH] i2c: tegra: Wait for config load atomically while in ISR

2021-01-11 Thread Dmitry Osipenko 
11.01.2021 16:55, Mikko Perttunen пишет:
> Upon a communication error, the interrupt handler can call
> tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen
> unless the current transaction was marked atomic. Since
> tegra_i2c_disable_packet_mode is only called from the interrupt path,
> make it use atomic waiting always.
> 
> Fixes: ede2299f7101 ("i2c: tegra: Support atomic transfers")
> Cc: sta...@vger.kernel.org
> Signed-off-by: Mikko Perttunen 
> ---
> This fixes constant spew for me while HDMI is connected to a
> powered off television.
> 
>  drivers/i2c/busses/i2c-tegra.c | 16 
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 6f08c0c3238d..4a7ff1840565 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -528,12 +528,12 @@ static void tegra_i2c_vi_init(struct tegra_i2c_dev 
> *i2c_dev)
>  
>  static int tegra_i2c_poll_register(struct tegra_i2c_dev *i2c_dev,
>  u32 reg, u32 mask, u32 delay_us,
> -u32 timeout_us)
> +u32 timeout_us, bool force_atomic)
>  {
>   void __iomem *addr = i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg);
>   u32 val;
>  
> - if (!i2c_dev->atomic_mode)
> + if (!i2c_dev->atomic_mode && !force_atomic)
>   return readl_relaxed_poll_timeout(addr, val, !(val & mask),
> delay_us, timeout_us);
>  
> @@ -560,7 +560,7 @@ static int tegra_i2c_flush_fifos(struct tegra_i2c_dev 
> *i2c_dev)
>   val |= mask;
>   i2c_writel(i2c_dev, val, offset);
>  
> - err = tegra_i2c_poll_register(i2c_dev, offset, mask, 1000, 100);
> + err = tegra_i2c_poll_register(i2c_dev, offset, mask, 1000, 100, 
> false);
>   if (err) {
>   dev_err(i2c_dev->dev, "failed to flush FIFO\n");
>   return err;
> @@ -569,7 +569,7 @@ static int tegra_i2c_flush_fifos(struct tegra_i2c_dev 
> *i2c_dev)
>   return 0;
>  }
>  
> -static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev)
> +static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev, 
> bool force_atomic)
>  {
>   int err;
>  
> @@ -579,7 +579,7 @@ static int tegra_i2c_wait_for_config_load(struct 
> tegra_i2c_dev *i2c_dev)
>   i2c_writel(i2c_dev, I2C_MSTR_CONFIG_LOAD, I2C_CONFIG_LOAD);
>  
>   err = tegra_i2c_poll_register(i2c_dev, I2C_CONFIG_LOAD, 0x,
> -   1000, I2C_CONFIG_LOAD_TIMEOUT);
> +   1000, I2C_CONFIG_LOAD_TIMEOUT, 
> force_atomic);
>   if (err) {
>   dev_err(i2c_dev->dev, "failed to load config\n");
>   return err;
> @@ -684,7 +684,7 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
>   if (i2c_dev->multimaster_mode && i2c_dev->hw->has_slcg_override_reg)
>   i2c_writel(i2c_dev, I2C_MST_CORE_CLKEN_OVR, I2C_CLKEN_OVERRIDE);
>  
> - err = tegra_i2c_wait_for_config_load(i2c_dev);
> + err = tegra_i2c_wait_for_config_load(i2c_dev, false);
>   if (err)
>   return err;
>  
> @@ -707,7 +707,7 @@ static int tegra_i2c_disable_packet_mode(struct 
> tegra_i2c_dev *i2c_dev)
>   if (cnfg & I2C_CNFG_PACKET_MODE_EN)
>   i2c_writel(i2c_dev, cnfg & ~I2C_CNFG_PACKET_MODE_EN, I2C_CNFG);
>  
> - return tegra_i2c_wait_for_config_load(i2c_dev);
> + return tegra_i2c_wait_for_config_load(i2c_dev, true);
>  }
>  
>  static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
> @@ -1090,7 +1090,7 @@ static int tegra_i2c_issue_bus_clear(struct i2c_adapter 
> *adap)
> I2C_BC_TERMINATE;
>   i2c_writel(i2c_dev, val, I2C_BUS_CLEAR_CNFG);
>  
> - err = tegra_i2c_wait_for_config_load(i2c_dev);
> + err = tegra_i2c_wait_for_config_load(i2c_dev, false);
>   if (err)
>   return err;
>  
> 

What about a simpler variant:

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 6f08c0c3238d..0727383f4940 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -533,7 +533,7 @@ static int tegra_i2c_poll_register(struct
tegra_i2c_dev *i2c_dev,
void __iomem *addr = i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg);
u32 val;

-   if (!i2c_dev->atomic_mode)
+   if (!i2c_dev->atomic_mode && !in_irq())
return readl_relaxed_poll_timeout(addr, val, !(val & mask),
  delay_us, timeout_us);

Re: [PATCH] i2c: tegra: Wait for config load atomically while in ISR

2021-01-11 Thread Mikko Perttunen 
Agreed that this is possibly not optimal, but this patch simply returns 
the behavior to what it was before "i2c: tegra: Support atomic 
transfers", fixing the overt issue.


Design fixes can be considered later, in a non-stable patch.

Mikko

On 1/11/21 4:31 PM, David Laight wrote:

From: Mikko Perttunen

Sent: 11 January 2021 13:56

Upon a communication error, the interrupt handler can call
tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen
unless the current transaction was marked atomic. Since
tegra_i2c_disable_packet_mode is only called from the interrupt path,
make it use atomic waiting always.


Spin-waiting in an ISR for anything that it makes sense to do
a sleep-wait for at other times is badly broken design.

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, 
UK
Registration No: 1397386 (Wales)

RE: [PATCH] i2c: tegra: Wait for config load atomically while in ISR

2021-01-11 Thread David Laight 
From: Mikko Perttunen
> Sent: 11 January 2021 13:56
> 
> Upon a communication error, the interrupt handler can call
> tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen
> unless the current transaction was marked atomic. Since
> tegra_i2c_disable_packet_mode is only called from the interrupt path,
> make it use atomic waiting always.

Spin-waiting in an ISR for anything that it makes sense to do
a sleep-wait for at other times is badly broken design.

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, 
UK
Registration No: 1397386 (Wales)

[PATCH] i2c: tegra: Wait for config load atomically while in ISR

2021-01-11 Thread Mikko Perttunen 
Upon a communication error, the interrupt handler can call
tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen
unless the current transaction was marked atomic. Since
tegra_i2c_disable_packet_mode is only called from the interrupt path,
make it use atomic waiting always.

Fixes: ede2299f7101 ("i2c: tegra: Support atomic transfers")
Cc: sta...@vger.kernel.org
Signed-off-by: Mikko Perttunen 
---
This fixes constant spew for me while HDMI is connected to a
powered off television.

 drivers/i2c/busses/i2c-tegra.c | 16 
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 6f08c0c3238d..4a7ff1840565 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -528,12 +528,12 @@ static void tegra_i2c_vi_init(struct tegra_i2c_dev 
*i2c_dev)
 
 static int tegra_i2c_poll_register(struct tegra_i2c_dev *i2c_dev,
   u32 reg, u32 mask, u32 delay_us,
-  u32 timeout_us)
+  u32 timeout_us, bool force_atomic)
 {
void __iomem *addr = i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg);
u32 val;
 
-   if (!i2c_dev->atomic_mode)
+   if (!i2c_dev->atomic_mode && !force_atomic)
return readl_relaxed_poll_timeout(addr, val, !(val & mask),
  delay_us, timeout_us);
 
@@ -560,7 +560,7 @@ static int tegra_i2c_flush_fifos(struct tegra_i2c_dev 
*i2c_dev)
val |= mask;
i2c_writel(i2c_dev, val, offset);
 
-   err = tegra_i2c_poll_register(i2c_dev, offset, mask, 1000, 100);
+   err = tegra_i2c_poll_register(i2c_dev, offset, mask, 1000, 100, 
false);
if (err) {
dev_err(i2c_dev->dev, "failed to flush FIFO\n");
return err;
@@ -569,7 +569,7 @@ static int tegra_i2c_flush_fifos(struct tegra_i2c_dev 
*i2c_dev)
return 0;
 }
 
-static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev)
+static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev, bool 
force_atomic)
 {
int err;
 
@@ -579,7 +579,7 @@ static int tegra_i2c_wait_for_config_load(struct 
tegra_i2c_dev *i2c_dev)
i2c_writel(i2c_dev, I2C_MSTR_CONFIG_LOAD, I2C_CONFIG_LOAD);
 
err = tegra_i2c_poll_register(i2c_dev, I2C_CONFIG_LOAD, 0x,
- 1000, I2C_CONFIG_LOAD_TIMEOUT);
+ 1000, I2C_CONFIG_LOAD_TIMEOUT, 
force_atomic);
if (err) {
dev_err(i2c_dev->dev, "failed to load config\n");
return err;
@@ -684,7 +684,7 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
if (i2c_dev->multimaster_mode && i2c_dev->hw->has_slcg_override_reg)
i2c_writel(i2c_dev, I2C_MST_CORE_CLKEN_OVR, I2C_CLKEN_OVERRIDE);
 
-   err = tegra_i2c_wait_for_config_load(i2c_dev);
+   err = tegra_i2c_wait_for_config_load(i2c_dev, false);
if (err)
return err;
 
@@ -707,7 +707,7 @@ static int tegra_i2c_disable_packet_mode(struct 
tegra_i2c_dev *i2c_dev)
if (cnfg & I2C_CNFG_PACKET_MODE_EN)
i2c_writel(i2c_dev, cnfg & ~I2C_CNFG_PACKET_MODE_EN, I2C_CNFG);
 
-   return tegra_i2c_wait_for_config_load(i2c_dev);
+   return tegra_i2c_wait_for_config_load(i2c_dev, true);
 }
 
 static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
@@ -1090,7 +1090,7 @@ static int tegra_i2c_issue_bus_clear(struct i2c_adapter 
*adap)
  I2C_BC_TERMINATE;
i2c_writel(i2c_dev, val, I2C_BUS_CLEAR_CNFG);
 
-   err = tegra_i2c_wait_for_config_load(i2c_dev);
+   err = tegra_i2c_wait_for_config_load(i2c_dev, false);
if (err)
return err;
 
-- 
2.30.0