Re: [PATCH] spi: prevent overriding established bus settings

Hi,

Any comments on the patch?

Best regards, Marcin

czw., 21 lis 2019 o 10:29 Marcin Wojtas mw@semihalf.com napisał(a):

• Simon

czw., 21 lis 2019 o 05:39 Marcin Wojtas mw@semihalf.com napisał(a):

...

The SPI stack relies on a proper bus speed/mode configuration by calling dm_spi_claim_bus(). However the hitherto code allowed to accidentally override those settings in the spi_get_bus_and_cs() routine.

The initially established speed could be discarded by using the slave platdata, which turned out to be an issue on the platforms whose slave maximum supported frequency is not on par with the maximum frequency of the bus controller.

This patch fixes above issue by configuring the bus from spi_get_bus_and_cs() only in case it was not done before.

Signed-off-by: Marcin Wojtas mw@semihalf.com

drivers/spi/spi-uclass.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c index 76c4b53..fcbe532 100644 --- a/drivers/spi/spi-uclass.c +++ b/drivers/spi/spi-uclass.c @@ -296,6 +296,7 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, { struct udevice *bus, *dev; struct dm_spi_slave_platdata *plat;

•   struct spi_slave *slave;
    bool created = false;
    int ret;
  
  

@@ -351,19 +352,20 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode, slave->dev = dev; }

•   plat = dev_get_parent_platdata(dev);
  

•   slave = dev_get_parent_priv(dev);
  
  

•   /* get speed and mode from platdata when available */
  

•   if (plat->max_hz) {
  

•           speed = plat->max_hz;
  

•           mode = plat->mode;
  

•   /*
  

•    * In case the operation speed is not yet established by
  

•    * dm_spi_claim_bus() ensure the bus is configured properly.
  

•    */
  

•   if (!slave->speed) {
  

•           ret = spi_claim_bus(slave);
  

•           if (ret)
  

•                   goto err;
    }
  

•   ret = spi_set_speed_mode(bus, speed, mode);
  

•   if (ret)
  

•           goto err;
  
    *busp = bus;
  

•   *devp = dev_get_parent_priv(dev);
  

•   *devp = slave;
    debug("%s: bus=%p, slave=%p\n", __func__, bus, *devp);
  
    return 0;
  

-- 2.7.4