Re: [PATCH 5/8] drm/ast: Hide Gens 1 to 3 TX detection in branch

[Jocelyn Falempe <jfalempe@redhat.com>]

On 17/01/2025 11:29, Thomas Zimmermann wrote:
> Gen7 only supports ASTDP. Gens 4 to 6 support various TX chips,
> except ASTDP. These boards detect the TX chips by reading the SoC
> scratch register as VGACRD1.
> 
> Gens 1 to 3 only support SIL164. These boards read the DVO bit from
> VGACRA3. Hence move this test behind a branch, so that it does not
> run on later generations.

Thanks, it looks good to me.

Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>   drivers/gpu/drm/ast/ast_main.c | 30 +++++++++++++++---------------
>   1 file changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
> index 474eb255b325b..50b57bc15d53c 100644
> --- a/drivers/gpu/drm/ast/ast_main.c
> +++ b/drivers/gpu/drm/ast/ast_main.c
> @@ -96,21 +96,21 @@ static void ast_detect_tx_chip(struct ast_device *ast, bool need_post)
>   	/* Check 3rd Tx option (digital output afaik) */
>   	ast->tx_chip = AST_TX_NONE;
>   
> -	/*
> -	 * VGACRA3 Enhanced Color Mode Register, check if DVO is already
> -	 * enabled, in that case, assume we have a SIL164 TMDS transmitter
> -	 *
> -	 * Don't make that assumption if we the chip wasn't enabled and
> -	 * is at power-on reset, otherwise we'll incorrectly "detect" a
> -	 * SIL164 when there is none.
> -	 */
> -	if (!need_post) {
> -		jreg = ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xa3, 0xff);
> -		if (jreg & 0x80)
> -			ast->tx_chip = AST_TX_SIL164;
> -	}
> -
> -	if (IS_AST_GEN4(ast) || IS_AST_GEN5(ast) || IS_AST_GEN6(ast)) {
> +	if (AST_GEN(ast) <= 3) {
> +		/*
> +		 * VGACRA3 Enhanced Color Mode Register, check if DVO is already
> +		 * enabled, in that case, assume we have a SIL164 TMDS transmitter
> +		 *
> +		 * Don't make that assumption if we the chip wasn't enabled and
> +		 * is at power-on reset, otherwise we'll incorrectly "detect" a
> +		 * SIL164 when there is none.
> +		 */
> +		if (!need_post) {
> +			jreg = ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xa3, 0xff);
> +			if (jreg & 0x80)
> +				ast->tx_chip = AST_TX_SIL164;
> +		}
> +	} else if (IS_AST_GEN4(ast) || IS_AST_GEN5(ast) || IS_AST_GEN6(ast)) {
>   		/*
>   		 * On AST GEN4+, look the configuration set by the SoC in
>   		 * the SOC scratch register #1 bits 11:8 (interestingly marked