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SubjectRe: [PATCH v2] hvc_dcc : add support to armv4 and armv5 core
On 8/31/2012 4:47 AM, Matthieu CASTET wrote:
> Signed-off-by: Matthieu Castet <matthieu.castet@parrot.com>

Please consider adding some sort of commit text. Does this add some new
feature I may want on some downstream distro kernel?

> @@ -51,7 +51,7 @@ static inline char __dcc_getchar(void)
> return __c;
> }
>
> -static inline void __dcc_putchar(char c)
> +static inline void __dcc_putchar_v6(char c)
> {
> asm volatile("mcr p14, 0, %0, c0, c5, 0 @ write a char"
> : /* no output register */
> @@ -59,6 +59,69 @@ static inline void __dcc_putchar(char c)
> isb();
> }
>
> +static int hvc_dcc_put_chars_v6(uint32_t vt, const char *buf, int count)
> +{
> + int i;
> +
> + for (i = 0; i < count; i++) {
> + while (__dcc_getstatus_v6() & DCC_STATUS_TX_V6)
> + cpu_relax();
> +
> + __dcc_putchar_v6(buf[i]);
> + }
> +
> + return count;
> +}

It's unfortunate that the main logic is duplicated. I wonder if we could
push the runtime decision slightly lower into the accessor functions
instead and make some new functions dcc_tx_busy() and dcc_rx_busy() or
something. Then these loops stay the same.

> +
> +static int hvc_dcc_get_chars_v6(uint32_t vt, char *buf, int count)
> +{
> + int i;
> +
> + for (i = 0; i < count; ++i)
> + if (__dcc_getstatus_v6() & DCC_STATUS_RX_V6)
> + buf[i] = __dcc_getchar_v6();
> + else
> + break;
> +
> + return i;
> +}
> +
> +static const struct hv_ops hvc_dcc_get_put_ops_v6 = {
> + .get_chars = hvc_dcc_get_chars_v6,
> + .put_chars = hvc_dcc_put_chars_v6,
> +};
> +
> +#define DCC_STATUS_RX (1 << 0)
> +#define DCC_STATUS_TX (1 << 1)
> +
> +/* primitive JTAG1 protocol utilities */

This comment doesn't tell me much. Remove it?

> +static inline u32 __dcc_getstatus(void)
> +{
> + u32 ret;
> +
> + asm __volatile__ ("mrc p14, 0, %0, c0, c0 @ read comms ctrl reg"
> + : "=r" (ret));

Can you use volatile instead of __volatile__ so that the file is consistent?

> +
> + return ret;
> +}
> +
> +static inline char __dcc_getchar(void)
> +{
> + char c;
> +
> + asm __volatile__ ("mrc p14, 0, %0, c1, c0 @ read comms data reg"
> + : "=r" (c));
> +

Do you see any multiple character inputs? I think you may need an isb
here similar to the v6/7 code and in the putchar as well.

> + return c;
> +}
> +
> +static inline void __dcc_putchar(unsigned char c)
> +{
> + asm __volatile__ ("mcr p14, 0, %0, c1, c0 @ write a char"
> + : /* no output register */
> + : "r" (c));
> +}
> +
> static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
> {
> int i;
>

--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.



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