linux-kernel - Re: [PATCH RFC 2/4] Bluetooth: btqca: Add WCN3988 support

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Message-Id: <CSK97HK2XBSR.1Q5K7TUE55HH7@otso>
Date:   Fri, 12 May 2023 13:14:18 +0200
From:   "Luca Weiss" <luca.weiss@...rphone.com>
To:     "Simon Horman" <simon.horman@...igine.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        "Eric Dumazet" <edumazet@...gle.com>,
        "Jakub Kicinski" <kuba@...nel.org>,
        "Paolo Abeni" <pabeni@...hat.com>,
        "Rob Herring" <robh+dt@...nel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        "Balakrishna Godavarthi" <bgodavar@...eaurora.org>,
        "Rocky Liao" <rjliao@...eaurora.org>,
        "Marcel Holtmann" <marcel@...tmann.org>,
        "Johan Hedberg" <johan.hedberg@...il.com>,
        "Luiz Augusto von Dentz" <luiz.dentz@...il.com>,
        "Andy Gross" <agross@...nel.org>,
        "Bjorn Andersson" <andersson@...nel.org>,
        "Konrad Dybcio" <konrad.dybcio@...aro.org>,
        <~postmarketos/upstreaming@...ts.sr.ht>,
        <phone-devel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-bluetooth@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH RFC 2/4] Bluetooth: btqca: Add WCN3988 support

Hi Simon,

On Mon May 1, 2023 at 3:11 PM CEST, Simon Horman wrote:
> On Fri, Apr 21, 2023 at 04:11:39PM +0200, Luca Weiss wrote:
> > Add support for the Bluetooth chip codenamed APACHE which is part of
> > WCN3988.
> > 
> > The firmware for this chip has a slightly different naming scheme
> > compared to most others. For ROM Version 0x0200 we need to use
> > apbtfw10.tlv + apnv10.bin and for ROM version 0x201 apbtfw11.tlv +
> > apnv11.bin
> > 
> > Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
> > ---
> >  drivers/bluetooth/btqca.c   | 13 +++++++++++--
> >  drivers/bluetooth/btqca.h   | 12 ++++++++++--
> >  drivers/bluetooth/hci_qca.c | 12 ++++++++++++
> >  3 files changed, 33 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
> > index fd0941fe8608..3ee1ef88a640 100644
> > --- a/drivers/bluetooth/btqca.c
> > +++ b/drivers/bluetooth/btqca.c
> > @@ -594,14 +594,20 @@ int qca_uart_setup(struct hci_dev *hdev, uint8_t baudrate,
> >  	/* Firmware files to download are based on ROM version.
> >  	 * ROM version is derived from last two bytes of soc_ver.
> >  	 */
> > -	rom_ver = ((soc_ver & 0x00000f00) >> 0x04) | (soc_ver & 0x0000000f);
> > +	if (soc_type == QCA_WCN3988)
> > +		rom_ver = ((soc_ver & 0x00000f00) >> 0x05) | (soc_ver & 0x0000000f);
> > +	else
> > +		rom_ver = ((soc_ver & 0x00000f00) >> 0x04) | (soc_ver & 0x0000000f);
>
> Hi Luca,
>
> perhaps it's just me. But I was wondering if this can be improved on a little.
>
> * Move the common portion outside of the conditional
> * And also, I think it's normal to use decimal for shift values.
>
> e.g.
> 	unsigned shift;
> 	...
>
> 	shift = soc_type == QCA_WCN3988 ? 5 : 4;
> 	rom_ver = ((soc_ver & 0x00000f00) >> shift) | (soc_ver & 0x0000000f);
>
> Using some helpers such as GENMASK and FIELD_PREP might also be nice.

While I'm not opposed to the idea, I'm not sure it's worth making
beautiful macros for this since - to my eyes - how the mapping of
soc_ver to firmware name works is rather obscure since the sources from
Qualcomm just have a static lookup table of soc_ver to firmware name so
doing this dynamically like here is different.

And I haven't looked at other chips that are covered there to see if
there's a pattern to this, for the most part it seems the original
formula works for most chips and the one I added works for WCN3988 (and
the other "APACHE" chips, whatever they are).

If a third way is added then I would say for sure this line should be
made nicer but for now I think it's easier to keep this as I sent it
because we don't know what the future will hold.

>
> >  
> >  	if (soc_type == QCA_WCN6750)
> >  		qca_send_patch_config_cmd(hdev);
> >  
> >  	/* Download rampatch file */
> >  	config.type = TLV_TYPE_PATCH;
> > -	if (qca_is_wcn399x(soc_type)) {
> > +	if (soc_type == QCA_WCN3988) {
> > +		snprintf(config.fwname, sizeof(config.fwname),
> > +			 "qca/apbtfw%02x.tlv", rom_ver);
> > +	} else if (qca_is_wcn399x(soc_type)) {
> >  		snprintf(config.fwname, sizeof(config.fwname),
> >  			 "qca/crbtfw%02x.tlv", rom_ver);
> >  	} else if (soc_type == QCA_QCA6390) {
> > @@ -636,6 +642,9 @@ int qca_uart_setup(struct hci_dev *hdev, uint8_t baudrate,
> >  	if (firmware_name)
> >  		snprintf(config.fwname, sizeof(config.fwname),
> >  			 "qca/%s", firmware_name);
> > +	else if (soc_type == QCA_WCN3988)
> > +		snprintf(config.fwname, sizeof(config.fwname),
> > +			 "qca/apnv%02x.bin", rom_ver);
> >  	else if (qca_is_wcn399x(soc_type)) {
> >  		if (ver.soc_id == QCA_WCN3991_SOC_ID) {
>
> Not strictly related to this patch, but while reviewing this I noticed that
> ver.soc_id is __le32 but QCA_WCN3991_SOC_ID is in host byteorder.
>
> Perhaps a cpu_to_le32() or le32_to_cpu() call is in order here?

Good catch, as you've seen I sent a patch separately to fix that. :)

Regards
Luca

>
> >  			snprintf(config.fwname, sizeof(config.fwname),
>
> ...