[U-Boot] [PATCH] dm: spi: prevent setting a speed of 0 Hz
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com ---
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c index e06a603ab1..41ecef77db 100644 --- a/drivers/spi/spi-uclass.c +++ b/drivers/spi/spi-uclass.c @@ -325,6 +325,8 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, if (!speed) { speed = plat->max_hz; mode = plat->mode; + if (!speed) + speed = 100000; } ret = spi_set_speed_mode(bus, speed, mode); if (ret)
Hi
On Thu, Jan 18, 2018 at 9:15 AM, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c index e06a603ab1..41ecef77db 100644 --- a/drivers/spi/spi-uclass.c +++ b/drivers/spi/spi-uclass.c @@ -325,6 +325,8 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, if (!speed) { speed = plat->max_hz; mode = plat->mode;
if (!speed)speed = 100000;
You should add a warming message
Michael
} ret = spi_set_speed_mode(bus, speed, mode); if (ret)-- 2.11.0
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On 18.01.2018 09:23, Michael Nazzareno Trimarchi wrote:
Hi
On Thu, Jan 18, 2018 at 9:15 AM, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c index e06a603ab1..41ecef77db 100644 --- a/drivers/spi/spi-uclass.c +++ b/drivers/spi/spi-uclass.c @@ -325,6 +325,8 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, if (!speed) { speed = plat->max_hz; mode = plat->mode;
if (!speed)speed = 100000;You should add a warming message
Hmm, I just copied what 'dm_spi_claim_bus' does some hundred lines above in the same file. Why should one code path warn when the other doesn't?
Simon
Michael
} ret = spi_set_speed_mode(bus, speed, mode); if (ret)-- 2.11.0
<snip>
Hi
On Thu, Jan 18, 2018 at 9:27 AM, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
On 18.01.2018 09:23, Michael Nazzareno Trimarchi wrote:
Hi
On Thu, Jan 18, 2018 at 9:15 AM, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c index e06a603ab1..41ecef77db 100644 --- a/drivers/spi/spi-uclass.c +++ b/drivers/spi/spi-uclass.c @@ -325,6 +325,8 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, if (!speed) { speed = plat->max_hz; mode = plat->mode;
if (!speed)speed = 100000;You should add a warming message
Hmm, I just copied what 'dm_spi_claim_bus' does some hundred lines above in the same file. Why should one code path warn when the other doesn't?
I just check this page but if you have some missing definition in device tree maybe make sense to make it visible
Michael
Simon
Michael
} ret = spi_set_speed_mode(bus, speed, mode); if (ret)-- 2.11.0
<snip>
Hi Simon,
On 18 January 2018 at 01:15, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
Another option is to have a sensible default when reading from the DT fails. See spi_slave_ofdata_to_platdata() - you can add the default there.
Would that work?
Regards, Simon
On 22.01.2018 01:29, Simon Glass wrote:
Hi Simon,
On 18 January 2018 at 01:15, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
Another option is to have a sensible default when reading from the DT fails. See spi_slave_ofdata_to_platdata() - you can add the default there.
Would that work?
This seems like a good idea, but I'm not sure it fixes my 'divide-by-zero' bug because that bug also triggered if the subnode of my spi controller was missing the compatible field for 'spi-flash'. I'd have to check that.
Regards, Simon
On Thursday 18 January 2018 01:45 PM, Simon Goldschmidt wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
As per doc/device-tree-bindings/spi/spi-bus.txt, spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz
IMO, the correct fix would be to error out with proper warning, if spi-max-frequency property is absent in DT.
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c index e06a603ab1..41ecef77db 100644 --- a/drivers/spi/spi-uclass.c +++ b/drivers/spi/spi-uclass.c @@ -325,6 +325,8 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, if (!speed) { speed = plat->max_hz; mode = plat->mode;
if (!speed)speed = 100000;
On 22.01.2018 06:04, Vignesh R wrote:
On Thursday 18 January 2018 01:45 PM, Simon Goldschmidt wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
As per doc/device-tree-bindings/spi/spi-bus.txt, spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz
IMO, the correct fix would be to error out with proper warning, if spi-max-frequency property is absent in DT.
By now, I think so, too. Fallback to 100.000 Hz really hurts when loading a 16 MByte fit image from qspi. A warning is required at least, but completely failing might be better indeed...
Regards, Simon
Signed-off-by: Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com
drivers/spi/spi-uclass.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c index e06a603ab1..41ecef77db 100644 --- a/drivers/spi/spi-uclass.c +++ b/drivers/spi/spi-uclass.c @@ -325,6 +325,8 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, if (!speed) { speed = plat->max_hz; mode = plat->mode;
if (!speed)speed = 100000;
On Thu, Jan 18, 2018 at 1:45 PM, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Better go-with default baudrate if speed == 0 this what usually does in remaining drivers.
On 22.01.2018 07:01, Jagan Teki wrote:
On Thu, Jan 18, 2018 at 1:45 PM, Simon Goldschmidt sgoldschmidt@de.pepperl-fuchs.com wrote:
When the device tree is missing a correct spi slave description below the bus, the 'set_speed' callback can be called with 'speed' == 0 Hz. At least with cadence qspi, this leads to a division by zero.
Prevent this by initializing speed to 100 kHz in this case, as is done in 'dm_spi_claim_bus'.
Better go-with default baudrate if speed == 0 this what usually does in remaining drivers.
That's what I did. I set a default value of 100 kHz. The difference seems to me that the remaining drivers are host drivers whereas I was trying to fix an invalid declaration of a df chip.
Regards, Simon
participants (5)
-
Jagan Teki -
Michael Nazzareno Trimarchi -
Simon Glass -
Simon Goldschmidt -
Vignesh R