Re: [PATCH v7 4/8] Bluetooth: btqca: Redefine qca_uart_setup() to generic function.

[Matthias Kaehlcke <mka@chromium.org>]

On Tue, Jun 19, 2018 at 12:39:07PM +0530, Balakrishna Godavarthi wrote:
> Hi Matthias,
> 
> Please find my comments inline.
> 
> On 2018-06-19 02:49, Matthias Kaehlcke wrote:
> > On Sat, Jun 16, 2018 at 11:57:14AM +0530, Balakrishna Godavarthi wrote:
> > > Redefinition of qca_uart_setup will help future Qualcomm Bluetooth
> > > SoC, to use the same function instead of duplicating the function.
> > > Added new arguments soc_type and soc_ver to the functions.
> > > 
> > > These arguments will help to decide type of firmware files
> > > to be loaded into Bluetooth chip.
> > > soc_type holds the Bluetooth chip connected to APPS processor.
> > > soc_ver holds the Bluetooth chip version.
> > > 
> > > Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
> > > ---
> > > 
> > > Changes in v7:
> > > 	* initial patch
> > > 	* redefined qca_uart_setup function to generic.
> > > 
> > > ---
> > >  drivers/bluetooth/btqca.c   | 23 ++++++++++++-----------
> > >  drivers/bluetooth/btqca.h   | 13 +++++++++++--
> > >  drivers/bluetooth/hci_qca.c |  3 ++-
> > >  3 files changed, 25 insertions(+), 14 deletions(-)
> > > 
> > > diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
> > > index c5cf9cab438a..f748730039cf 100644
> > > --- a/drivers/bluetooth/btqca.c
> > > +++ b/drivers/bluetooth/btqca.c
> > > @@ -327,9 +327,9 @@ int qca_set_bdaddr_rome(struct hci_dev *hdev,
> > > const bdaddr_t *bdaddr)
> > >  }
> > >  EXPORT_SYMBOL_GPL(qca_set_bdaddr_rome);
> > > 
> > > -int qca_uart_setup(struct hci_dev *hdev, uint8_t baudrate)
> > > +int qca_uart_setup(struct hci_dev *hdev, uint8_t baudrate, uint8_t
> > > soc_type,
> > 
> > Use 'enum qca_btsoc_type' as type for 'soc_type'.
> > 
> 
> [Bala]: will update.
> 
> > > +		   u32 soc_ver)
> > >  {
> > > -	u32 rome_ver = 0;
> > >  	struct rome_config config;
> > >  	int err;
> > > 
> > > @@ -337,19 +337,20 @@ int qca_uart_setup(struct hci_dev *hdev,
> > > uint8_t baudrate)
> > > 
> > >  	config.user_baud_rate = baudrate;
> > > 
> > > -	/* Get QCA version information */
> > > -	err = qca_read_soc_version(hdev, &rome_ver);
> > > -	if (err < 0 || rome_ver == 0) {
> > > -		bt_dev_err(hdev, "QCA Failed to get version %d", err);
> > > -		return err;
> > > +	if (!soc_ver) {
> > > +		/* Get QCA version information */
> > > +		err = qca_read_soc_version(hdev, &soc_ver);
> > > +		if (err < 0 || soc_ver == 0) {
> > > +			bt_dev_err(hdev, "QCA Failed to get version %d", err);
> > > +			return err;
> > > +		}
> > > +		bt_dev_info(hdev, "QCA controller version 0x%08x", soc_ver);
> > >  	}
> > 
> > Why is this needed? A caller that passes in soc_ver = 0 could just
> > call qca_read_soc_version() themselves.
> [Bala]: hci_qca support two chip one ROME (already up-streamed) and other
> wcn3990.
>         there setup sequence differs.
> 
>         wcn3900:
>         1. set baudrate to 115200
>         2. read soc version
>         3. set baudarte to 3.2Mbps
>         4. download firmware. (calls qca_uart_setup)
> 
>        ROME:
>        1. set baudrate to 3.0 mbps
>        2. calls qca_uart_setup to read soc version and download firmware.
> 
>       so to make use of existing function qca_setup_uart(). passing soc_ver
> as argument.
>       if soc_ver is zero, then read soc version (i.e. for ROME chip).
> 
>       Pls let me know, if you have any queries.

I don't really understand this argumentation. Let's look at the code
at the end of this series, where both Rome and wcn3900 are supported:

https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1045608/6/drivers/bluetooth/hci_qca.c#1059

The version could be read (for Rome only) after setting the operating speed:

https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1045608/6/drivers/bluetooth/hci_qca.c#1111

I concede that having two "if (qcadev->btsoc_type == XYZ)" branches in
qca_setup() is kinda ugly, but I think it's still better than the
conditional call of qca_read_soc_version() in qca_uart_setup().