this driver relies on exposing a char device to userspace to tx messages. Every message can be sent using different trasmitter settings such so the tx_cfg must be written before sending any messages. Failing to do so will cause the message to fail silently depending on printk/dynamic_debug settings which makes it hard to troubleshoot. This patch add a control variable that will get initialized once tx_cfg is set for the fd used when interacting with the char device. Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@xxxxxxxxx> --- Patch dependency: - This patch needs the patch below to be applied first as both tweak the same file. https://lore.kernel.org/lkml/20220108212728.GA7784@xxxxxxxxxxxxxxx/ meta-comments: - I'm not entirely sure if -EPERM is the best error code to return here, I'm taking suggestions --- drivers/staging/pi433/pi433_if.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c index 051c9052aeeb..3e9913f4bc7d 100644 --- a/drivers/staging/pi433/pi433_if.c +++ b/drivers/staging/pi433/pi433_if.c @@ -108,6 +108,9 @@ struct pi433_device { struct pi433_instance { struct pi433_device *device; struct pi433_tx_cfg tx_cfg; + + /* control flags */ + bool tx_cfg_initialized; }; /*-------------------------------------------------------------------------*/ @@ -823,6 +826,16 @@ pi433_write(struct file *filp, const char __user *buf, if (count > MAX_MSG_SIZE) return -EMSGSIZE; + /* + * check if tx_cfg has been initialized otherwise we won't be able to + * config the RF trasmitter correctly due to invalid settings + */ + if (!instance->tx_cfg_initialized) { + dev_dbg(device->dev, + "write: failed due to uninitialized tx_cfg"); + return -EPERM; + } + /* * write the following sequence into fifo: * - tx_cfg @@ -897,6 +910,7 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) return -EFAULT; mutex_lock(&device->tx_fifo_lock); memcpy(&instance->tx_cfg, &tx_cfg, sizeof(struct pi433_tx_cfg)); + instance->tx_cfg_initialized = true; mutex_unlock(&device->tx_fifo_lock); break; case PI433_IOC_RD_RX_CFG: @@ -950,7 +964,7 @@ static int pi433_open(struct inode *inode, struct file *filp) /* setup instance data*/ instance->device = device; instance->tx_cfg.bit_rate = 4711; - // TODO: fill instance->tx_cfg; + instance->tx_cfg_initialized = false; /* instance data as context */ filp->private_data = instance; -- 2.25.4
