Crashdump collection is based on the DLOAD bit of TCSR register.
To retain other bits, we read the register and modify only the
DLOAD bit as the other bits have their own significance.

Co-developed-by: Poovendhan Selvaraj <quic_poovendh@quicinc.com>
Signed-off-by: Poovendhan Selvaraj <quic_poovendh@quicinc.com>
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Tested-by: Kathiravan Thirumoorthy <quic_kathirav@quicinc.com> # IPQ9574 and IPQ5332
---
 drivers/firmware/qcom_scm.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 084e4782b88d..da3d028f6451 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -4,6 +4,8 @@
  */
 
 #include <linux/arm-smccc.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/cpumask.h>
@@ -27,6 +29,10 @@
 static bool download_mode = IS_ENABLED(CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT);
 module_param(download_mode, bool, 0);
 
+#define QCOM_DLOAD_MASK		GENMASK(5, 4)
+#define QCOM_DLOAD_FULLDUMP	0x1
+#define QCOM_DLOAD_NODUMP	0x0
+
 struct qcom_scm {
 	struct device *dev;
 	struct clk *core_clk;
@@ -518,6 +524,7 @@ static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
 
 static void qcom_scm_set_download_mode(bool enable)
 {
+	u32 val = enable ? QCOM_DLOAD_FULLDUMP : QCOM_DLOAD_NODUMP;
 	bool avail;
 	int ret = 0;
 
@@ -527,8 +534,9 @@ static void qcom_scm_set_download_mode(bool enable)
 	if (avail) {
 		ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
 	} else if (__scm->dload_mode_addr) {
-		ret = qcom_scm_io_writel(__scm->dload_mode_addr,
-				enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
+		ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
+					       QCOM_DLOAD_MASK,
+					       FIELD_PREP(QCOM_DLOAD_MASK, val));
 	} else {
 		dev_err(__scm->dev,
 			"No available mechanism for setting download mode\n");
-- 
2.7.4

On Wed, 4 Oct 2023 at 20:28, Mukesh Ojha <quic_mojha@quicinc.com> wrote:
>
> Crashdump collection is based on the DLOAD bit of TCSR register.
> To retain other bits, we read the register and modify only the
> DLOAD bit as the other bits have their own significance.

Nit: please take a look at
`Documentation/process/submitting-patches.rst`: `Describe your changes
in imperative mood'.

We do not read registers. Driver does. Nevertheless, this is a minor
issue, which shouldn't prevent this patch from being applied.

>
> Co-developed-by: Poovendhan Selvaraj <quic_poovendh@quicinc.com>
> Signed-off-by: Poovendhan Selvaraj <quic_poovendh@quicinc.com>
> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
> Tested-by: Kathiravan Thirumoorthy <quic_kathirav@quicinc.com> # IPQ9574 and IPQ5332

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> ---
>  drivers/firmware/qcom_scm.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 084e4782b88d..da3d028f6451 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -4,6 +4,8 @@
>   */
>
>  #include <linux/arm-smccc.h>
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
>  #include <linux/clk.h>
>  #include <linux/completion.h>
>  #include <linux/cpumask.h>
> @@ -27,6 +29,10 @@
>  static bool download_mode = IS_ENABLED(CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT);
>  module_param(download_mode, bool, 0);
>
> +#define QCOM_DLOAD_MASK                GENMASK(5, 4)
> +#define QCOM_DLOAD_FULLDUMP    0x1
> +#define QCOM_DLOAD_NODUMP      0x0

Nit: it might be better to move these defines after all struct definitions.

> +
>  struct qcom_scm {
>         struct device *dev;
>         struct clk *core_clk;
> @@ -518,6 +524,7 @@ static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
>
>  static void qcom_scm_set_download_mode(bool enable)
>  {
> +       u32 val = enable ? QCOM_DLOAD_FULLDUMP : QCOM_DLOAD_NODUMP;
>         bool avail;
>         int ret = 0;
>
> @@ -527,8 +534,9 @@ static void qcom_scm_set_download_mode(bool enable)
>         if (avail) {
>                 ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
>         } else if (__scm->dload_mode_addr) {
> -               ret = qcom_scm_io_writel(__scm->dload_mode_addr,
> -                               enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
> +               ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
> +                                              QCOM_DLOAD_MASK,
> +                                              FIELD_PREP(QCOM_DLOAD_MASK, val));
>         } else {
>                 dev_err(__scm->dev,
>                         "No available mechanism for setting download mode\n");
> --
> 2.7.4
>


-- 
With best wishes
Dmitry