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Message-ID: <CACeCKad1suBNrpPOtKnHaLZmLEpgV4ExA53ermqv50viSSnLdA@mail.gmail.com>
Date: Mon, 6 Feb 2023 11:55:57 -0800
From: Prashant Malani <pmalani@...omium.org>
To: Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
Cc: bleung@...omium.org, groeck@...omium.org,
chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org,
rajat.khandelwal@...el.com
Subject: Re: [PATCH] platform/chrome: Avoid fetching the type-C parameters again
Hi Rajat,
Please use the right header in the commit message. There are plenty of
examples in the git log.
On Sun, Feb 5, 2023 at 11:34 PM Rajat Khandelwal
<rajat.khandelwal@...ux.intel.com> wrote:
>
> The struct 'cros_typec_port' incorporates three type-C parameters,
> 'ori_sw', 'retimer', and 'mux'.
> These parameters in the struct 'typec_port' are being already
> configured when 'typec_register_port' is being called.
>
> The bigger picture - 'typec_register_port' can return an error and
> the type-C parameters could go unconfigured. However, the callback
> will return EPROBE_DEFER and the driver will again be getting probed
> trying to configure them again.
> However, currently, they are again tried to get fetched for the
> 'cros_typec_port' struct, which sometimes could result in an error
> and these parameters could go unconfigured (no provision of deferring
> the probe in this case, so we are left with unconfigured parameters).
This is by design. If the switch handles cannot be obtained for any reason
other that -EPROBE_DEFER, we will not re-attempt to acquire them, and
should continue driver probe and carry on with limited functionality.
If there is a sporadic error other than -EPROBE_DEFER, that points to a
deeper issue in firmware which should be investigated.
>
> Hence, assign the parameters to the corresponding ones in the struct
> 'typec_port' after they are fetched in 'typec_register_port'.
>
> Signed-off-by: Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
> ---
> drivers/platform/chrome/cros_ec_typec.c | 58 ++++++++++---------------
> 1 file changed, 22 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> index 001b0de95a46..0265c0d38bd6 100644
> --- a/drivers/platform/chrome/cros_ec_typec.c
> +++ b/drivers/platform/chrome/cros_ec_typec.c
> @@ -24,6 +24,8 @@
> #include <linux/usb/typec_tbt.h>
> #include <linux/usb/role.h>
>
> +#include "../../usb/typec/class.h"
That is a local header. We cannot use it outside of drivers/usb/typec/
> +
> #define DRV_NAME "cros-ec-typec"
>
> #define DP_PORT_VDO (DP_CONF_SET_PIN_ASSIGN(BIT(DP_PIN_ASSIGN_C) | BIT(DP_PIN_ASSIGN_D)) | \
> @@ -141,47 +143,17 @@ static int cros_typec_parse_port_props(struct typec_capability *cap,
> return 0;
> }
>
> -static int cros_typec_get_switch_handles(struct cros_typec_port *port,
> - struct fwnode_handle *fwnode,
> - struct device *dev)
> +static int cros_typec_get_role_switch_handle(struct cros_typec_port *port,
> + struct fwnode_handle *fwnode,
> + struct device *dev)
> {
> - port->mux = fwnode_typec_mux_get(fwnode, NULL);
> - if (IS_ERR(port->mux)) {
> - dev_dbg(dev, "Mux handle not found.\n");
> - goto mux_err;
> - }
> -
> - port->retimer = fwnode_typec_retimer_get(fwnode);
> - if (IS_ERR(port->retimer)) {
> - dev_dbg(dev, "Retimer handle not found.\n");
> - goto retimer_sw_err;
> - }
> -
> - port->ori_sw = fwnode_typec_switch_get(fwnode);
> - if (IS_ERR(port->ori_sw)) {
> - dev_dbg(dev, "Orientation switch handle not found.\n");
> - goto ori_sw_err;
> - }
> -
> port->role_sw = fwnode_usb_role_switch_get(fwnode);
> if (IS_ERR(port->role_sw)) {
> dev_dbg(dev, "USB role switch handle not found.\n");
> - goto role_sw_err;
> + return -ENODEV;
> }
>
> return 0;
> -
> -role_sw_err:
> - typec_switch_put(port->ori_sw);
> - port->ori_sw = NULL;
> -ori_sw_err:
> - typec_retimer_put(port->retimer);
> - port->retimer = NULL;
> -retimer_sw_err:
> - typec_mux_put(port->mux);
> - port->mux = NULL;
> -mux_err:
> - return -ENODEV;
> }
>
> static int cros_typec_add_partner(struct cros_typec_data *typec, int port_num,
> @@ -363,6 +335,18 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
> return 0;
> }
>
> +static void cros_typec_copy_port_params(struct cros_typec_port *cros_port)
> +{
> + struct typec_port *port = cros_port->port;
> +
> + if (IS_ERR_OR_NULL(port))
> + return;
> +
> + cros_port->mux = port->mux;
> + cros_port->retimer = port->retimer;
> + cros_port->ori_sw = port->sw;
> +}
Sorry, but this is not the right approach. These handles are
ref-counted. We intentionally
take extra references to these using the provided API. Please don't
use raw references like this.
Also, if the fwnode_*_get() functions are failing, why are we to
assume that they worked for the
Type-C class code (that code uses the same functions) [1] ?
This approach is not right.
BR,
-Prashant
[1] https://elixir.bootlin.com/linux/v6.2-rc7/source/drivers/usb/typec/class.c#L2317
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